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Wilderness hikers: 
  A wilderness trail may not be signed or passable or even followable  
Check the current trail conditions rating  

Big Sur Trailmap Garmin maps

Map accuracy:  These Garmin map versions of the on-line Big Sur Trailmap provide accurate trail and camp locations based on local knowledge (mostly GPS'd), also locally-known "use trails", water sources, waterfalls, and other features in the Ventana and Silver Peak Wilderness areas and in Big Sur state parks. 

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[last map update: Jun 12, 2024]

Note:  If you own a smartphone but not a GPS, consider using a smartphone app as an "electronic map" - it may well meet all your needs and requires less learning.  If you later want a more rugged, and in some ways more capable, "electronic map", you can step up to a GPS.  For information on smartphone apps, see Big Sur Trailmap for Smartphones.

Users of a Garmin outdoor GPS [e.g. GPSMAP, Oregon, eTrex 20/30] and some Garmin wearables [e.g. Forerunner 945, Fenix 5/6] can load this version of the Big Sur Trailmap directly into their GPS.  It displays all Big Sur Trailmap features - including "historic"/"lost" trails and camps (but the former are only displayed, i.e. are excluded from routes)(If you want to display those, you must separately upload their GPX data).   The "with topography" version also displays 40ft-interval contour lines and intermittent+perennial streams, whereas the "sans topography" version uses a transparent background so features on another loaded map, such as topography/streams/roads/etc, can also be seen (but be warned: that map may also display trails/roads/etc which do not actually exist!) Screen snapshots below depict the Sykes Camp area, displaying a trail, a use trail, and a camp - note that moving the map pointer over the camp or trail or use trail has caused its abbreviated name to be displayed.   For a depiction of these trails, camps, and other features in a browser, on a quadrangle/terrain/satellite background, see the Big Sur Ventana/SilverPeak Trailmap home page. 










Trailmap Legend (icons and line symbology)

Garmin trailmaps do not display any closures !
(due to the ephemeral nature of closures)
Trail and road closure information must be obtained from the on-line interactive maps,
e.g.  trail conditions interactive map


(1)  Choose installation method
(simplest = Method 1 "Direct Installation" below)

(2)  Choose map type desired
(WITH/SANS Topography+Streams)

(3)  Download file for chosen installation method and map type
(Method 1 = .IMG file)

(4)  Follow file installation procedure
(Method 1 = copy .IMG file to GPS)

(5)  Activate map on GPS

       I am not a Mac user so instructions for it are sketchy
       Newer Windows systems want to protect you from malicious files, so may display warnings and/or require additional confirmation before downloading or installing these files (because my site does not have a identifying "certificate", which requires $ and administrative time) - those warnings should be ignored
       Windows systems may complain about an "invalid" image file (because the Garmin-format .IMG extension is the same as used by Windows image files) - those warnings should be ignored

     If you find a problem please let me know since the updating is automatic so I do not individually test these files.
     (FYI the most severe problem I've encountered with a bad map is GPS lockup, producing a frozen display which slowly fades - the bad map must then be deleted or overwritten.)



Method 1
Direct Installation to GPS
(downloaded .IMG file is copied to a GPS memory directory)

Method 2a
Garmin BaseCamp (app) Installation to PC using Windows registry installation
(downloaded .exe file is executed on a PC)

Method 2b
Garmin BaseCamp (app) Installation to PC/Mac using Gmap installation
(downloaded .zip file is extracted on a PC/Mac)


Method 1
Direct installation to your GPS memory via USB transfer from your PC/Mac
Simplest, requiring only basic PC/Mac file copy+paste knowledge.
But only installs to GPS - trailmap will not be available on any PC/Mac software. 
(also used for "Supplementary Overlay") 

Methods 2a,2b
Installation of Garmin BaseCamp app to PC/Mac with later transfer to GPS
Installs Garmin BaseCamp software to your PC/Mac, which can then transfer the trailmap to a GPS.
This allows trailmap use in software on your PC/Mac in addition to on your GPS.
Method 2a
Registry Install: (Windows only) 
using an executable file, ala the usual Windows installation experience
(this allows easy replacement of an existing Big Sur Trailmap in BaseCamp - it is the method I personally use, so I have the trailmap available on both my PC and my GPS)
Method 2b
Garmin Map (Gmap) Install: (Windows and Mac) 
for Macs users and for Windows users who wish to avoid possible registry problems. 
Jan 2017 update:  installation of BaseCamp will display the Big Sur Trailmap and allow routing on your Mac but cannot transfer the map to a GPS.  To load the map to your GPS you must use the "Direct Installation" method (1).  For further info, see the detailed installation instructions below. 


• Line+Icon SIZE
3 choices:  SMALL  *OR*  MEDIUM  *OR*  LARGE

• WITH/SANS Topography+Streams 
2 choices:  WITH  *OR*  SANS (without)

The "SANS" version is transparent so if desired it can be displayed above an underlying topographic map, such as Garmin's "Topo24K" maps) - but beware: any incorrect info on the other map, such as the camp locations in "Topo24K", will also be displayed, which can be confusing!  To avoid such problems, I recommend loading the non-transparent "WITH" version for anyone having a newer GPS which can enable/disable individual maps, even if you have another map loaded - then only Trailmap data will be displayed inside the Trailmap region, with the other map being displayed outside that region.  If the other map has info that you wish to use, such as roads not depicted on the Trailmap, I recommend disabling the non-transparent Trailmap map to allow the other map to be displayed when needed, then re-enabling the Trailmap for hiking. 


Files for each installation method and map type
Download the appropriate file

Note:  On small-screens, this table is horizontally scrollable
Routeable Trailmap
WITH Topography+Streams
(non-transparent background)
SANS Topography+Streams
(transparent background)
SMALL Lines+Icons Method 1
Direct GPS Install
(.IMG file)

Method 2a
BaseCamp Windows Registry Install
(.exe file)

Method 2b
BaseCamp Garmin Map Install
(.zip file)
Method 1
Direct GPS Install
(.IMG file)

Method 2a
BaseCamp Windows Registry Install
(.exe file)

Method 2b
BaseCamp Garmin Map Install
(.zip file)
MEDIUM Lines+Icons Method 1
Direct GPS Install
(.IMG file)

Method 2a
BaseCamp Windows Registry Install
(.exe file)

Method 2b
BaseCamp Garmin Map Install
(.zip file)
Method 1
Direct GPS Install
(.IMG file)

Method 2a
BaseCamp Windows Registry Install
(.exe file)

Method 2b
BaseCamp Garmin Map Install
(.zip file)
LARGE Lines+Icons Method 1
Direct GPS Install
(.IMG file)

Method 2a
BaseCamp Windows Registry Install
(.exe file)

Method 2b
BaseCamp Garmin Map Install
(.zip file)
Method 1
Direct GPS Install
(.IMG file)

Method 2a
BaseCamp Windows Registry Install
(.exe file)

Method 2b
BaseCamp Garmin Map Install
(.zip file)

To avoid complexity, the above Big Sur Trailmap Garmin files do not display National Forest, State Park, or Wilderness boundary lines.  If desired, these boundaries can also be displayed by downloading this separate Big Sur NF-SP-Wilderness Boundary overlay map which is transferred to the GPS using the "Direct GPS Install" method described below.  When "Enabled", this transparent-background map displays National Forest (solid brown line), State Park (solid green line), and Wilderness (yellow line with black borders) boundaries on top of the Trailmap features. 


(uses direct PC-to-GPS data transfer via USB cable)

Copy downloaded file to GPS "Garmin" subdirectory

Detailed steps:
(lots of gory detail, just in case is needed/useful)

Please follow the instructions carefully and exactly - haste makes waste!  Do not delete any file not named "BigSurTrailmap" - if you mistakenly delete a needed system file, the GPS not operate (and recovery is difficult) ! 

  Download:  Download desired "Direct GPS Install" file

  Connect GPS to PC:  You must put your GPS into "USB Mass Storage" mode, which directly connects the GPS memory/storage to the PC.  First turn your GPS off, then connect a USB cable from your GPS to your PC.  Then
On a newer GPS, such as Oregon, GPSMAP62, and eTrex 20/30:
  The GPS will automatically turn on - wait for a "USB Mass Storage mode" screen to appear (either a PC-cabled-to-GPS or a horizontally-pointing trident, sort of) 
On an older GPS, such as GPSMAP60:
  Turn GPS on, select "Main Menu""Setup""Interface""USB Mass Storage" (a "PC-cabled-to-GPS" screen will appear when USB Mass Storage mode is entered) 

  Display GPS memory directory:  Wait for the PC to recognize that a new device has been attached, which is often indicated by a beep from the PC.  On many PCs, a pop-up will then display an "Autoplay" window - you should then click "Open folder to view files using Windows Explorer" which will open at the (highlighted) GPS device -- its name is GPS model and PC specific, an example being "Garmin Oregon (G:)".  It's subdirectories should be displayed, one of which will be "Garmin" (can be capitalized). If that pop-up does not appear, you must then open your PC's "Windows Explorer" program and find the GPS device that has been installed.  If the device's subdirectories are not displayed, then expand (click on the "+") to reveal the "Garmin" subdirectory.  And if your GPS has a microSD card, that device should also be displayed in Windows Explorer, e.g as "Removeable Disk (H:)", and should also have a "Garmin" subdirectory. 

  Copy downloaded file to GPS:  Use Windows Explorer to copy the Garmin-format Trailmap file you downloaded, "BigSurTrailmapWithTopo.IMG" or "BigSurTrailmapSansTopo.IMG", to a "Garmin" subdirectory on your GPS, either in the GPS memory or on the microSD card memory (if installed). 

  Special step for older GPSes:  this special step is NOT NEEDED for newer GPSes such as GPSMAP 62, Oregon, and eTrex 20/30 - do not do this step unless you know it is necessary!  It is needed for older units, such as the GPSMAP60 and pre-20/30 eTrex, which can only have one active map file (though that one file can contain many different individual maps) which must have the Garmin-determined name "gmapsupp.img" (can be capitalized).  If yours is such a GPS, it may already have an existing "gmapsupp.img" file in its "Garmin" directory, in which case it must be replaced with the BigSurTrailmap file - if you wish to preserve that old map data for use at a later time, you must then EITHER (1) rename it on the GPS (e.g. to old-gmapsupp.img) OR (2) move it to the PC for storage OR (3) do both for safety (recommended!).  If you do not wish to preserve it, then delete it.  Now re-name the "BigSurTrailmapWithTopo.IMG" or "BigSurTrailmapSansTopo.IMG" file just loaded onto the GPS's Garmin directory to "gmapsupp.img", so it will become the active map. 

  Disconnect GPS from PC:  Instead of simply unplugging the GPS from the USB cable, to safely remove the USB-enabled GPS it's best to, on the Windows PC, click on the "Open/Close Devices" icon (often a little USB plug and green circle with check mark inside, which should have appeared when the USB Mass Storage mode was established), then click "Eject USB Mass Storage Device" or "Eject (your device name)" , then after the "Safe to remove hardware" message appears the GPS can be disconnected from the USB cable. 

  Display GPS map:  Re-start the GPS - the Big Sur Trailmap should now display in the Big Sur region.  On newer GPS's, one can choose to enable/disable individual map files, generally via "Main Menu""Setup""Map""Map Information".  The Big Sur Trailmap will be indicated by "BigSurTrailmap" - and on some units, e.g. an Oregon, a second "BigSurTrailmap" map with topography+stream data will be found if you installed the version containing those and each map is "enabled" or "disabled" individually.  For additional information see How To Change Which Map Is Displayed On A Garmin GPS

  Usage notes:  The Big Sur Trailmap only takes 1 MB of storage SANS Topography and 44 MB WITH Topography, so if you have a newer GPS and plan to hike Big Sur again, you can just "disable" it as described in the last step, so it can be simply "enabled" on your next hike.  On an older GPS, which required the "special step" above, if you wish to preserve the Big Sur Trailmap for later use you can follow the above steps to again connect the GPS to the PC in USB Mass Storage mode and use Windows Explorer to go to your GPS's "Garmin" directory and reverse the "special step", i.e. re-name "gmapsupp.img" to "BigSurTrailmapWithTopo.IMG" or "BigSurTrailmapSansTopo.IMG" and then restore the original "gmapsupp.img" - or if you wish to restore your GPS to its original condition, then delete the Big Sur Trailmap from your GPS's "Garmin" directory. 

(uses direct Mac-to-GPS data transfer via USB cable)

The above detailed instructions for a PC should also work for a Mac with Mac-specific copying methods replacing the PC-specific ones.  In particular, Einar Vollset reports the following abbreviated procedure worked for his Oregon 600:
Please follow the instructions carefully and exactly - haste makes waste!  Do not delete any files - if you mistakenly delete a needed system file, the GPS not operate (and recovery is difficult)! 

  Download desired "Direct GPS Install" .IMG file

  Connect GPS via USB cable and turn on GPS

  Find GARMIN in the "Devices" Menu in Finder

  Drag the .IMG file into the "Garmin" folder under the GARMIN device - note: do not put it into the "Custom Maps" folder

  Disconnect and restart the GPS - map appears in Big Sur region

    [Note: the BaseCamp Windows PC version is found here.]
    This procedure executes a program which installs the Big Sur Trailmap into a Windows PC using the Windows Registry. 

•  Ensure that BaseCamp is not running! 

•  Run (execute) the downloaded installation file "BigSurTrailmapWithTopo_install.exe" or "BigSurTrailmapSansTopo_install.exe" (generally by double-clicking on its icon) and follow its popup instructions - IF ASKED what directory the files should be installed to, use C:\Garmin.  This creates a "BigSurTrailmap" background map option in BaseCamp (selected via a menu on the toolbar). 

(To uninstall from BaseCamp:  use the "Control Panel""Programs and Features" - find "Big Sur Trailmap", then right-click "Uninstall".)

    I am not going to treat BaseCamp software use - you can find a brief tutorial at the following link:  How To Load Maps On My Garmin GPS Unit (which includes instructions for a Mac).  Do note that you can use BaseCamp "Install Maps" to install the map onto your GPS - but if updating a previously installed Big Sur Trailmap on the GPS you will likely need to do so in two steps, first using "Install Maps" to remove the existing GPS map and then using "Install Maps" to add the new map. 

    If installing on Windows 7 (8/10?) 64-bit PC with newly installed BaseCamp:  [Jan 2015]  Some attempts to install this map into an "unused" (newly installed) BaseCamp on a Windows 7 64-bit PC have been initially unsuccessful - the map installation goes normally and "Big Sur Trailmap" is found in the Registry ["Control Panel"->"Programs and Features" (Windows 7)] but does not appear in BaseCamp.  The current fix is to first install a map found here (which uses a different installer, producing a "used" BaseCamp), then install the Trailmap, then uninstall the first map!  Apparently the problem results from "a minor change in how some keys are handled by the operating system which prevented the maps created with the old installer from appearing in Basecamp - this only affects computers running Windows 7 64-bit".  It also does not seems to affect previously installed versions of BaseCamp, since I myself run BaseCamp on a Windows 7 64-bit PC but have no difficulty in upgrading (or removing and re-installing) the Trailmap.  Alternatively, you can use the "Garmin Map Install" (Gmap) installation procedure described below.

    Windows 10 users:  Registry-based programs can encounter problems in Windows 10.  If such occurs, downloading and installing the "Gmap" ("Garmin Map Install") may work better for you.  Gmap installation for a Mac is described in the following section, but I have no personal experience with Windows to report.  If you gain some, I would appreciate a report on what worked for you.

  Jan 2017 update: For Mac users:  while installation to BaseCamp will display the Big Sur Trailmap and allow routing, trying to then transfer it to a GPS using BaseCamp's "Install Maps" now FAILS either by not showing a "Big Sur Trailmap" selection or with a message "There is a problem ..." .  For a Mac user, currently the only way of loading the map to your GPS is using the "Direct Installation" method.   If I find a solution to this problem I will delete this message.  (But I might later make a change which unknowingly fixes this problem - if a Mac user later finds a BaseCamp install to GPS works for them, please let me know!)

    [Note: the latest BaseCamp Mac version is found here]

    This alternative procedure installs a Garmin-format "Gmap" file into a Mac or Windows PC - it is provided for Mac or other users who are unable, or do not wish, to use the "Registry Installation" described above.  Note that this procedure does not use an installation program and so requires some basic computer skills/knowledge.  Also, it will not work for older BaseCamp versions. 

[Note: these instructions use info supplied by others, as I cannot test Mac usage - if it works or doesn't work for you, please let me know - I'll then remove or amend this message]

•  BaseCamp must already be installed - but not running!

•  Double-click on the downloaded "Garmin Map Install", "" (a zip format file) to extract the "BigSurTrailmap...gmap" folder file within it

•  Double-click on the extracted file to run "MapManager" (which should automatically be called if BaseCamp is installed). 

•  Follow its instructions to complete installation.  The trailmap will then appear as a background map selection in BaseCamp when next started. 

    [Note: the latest BaseCamp PC version is found here]

•  BaseCamp must already be installed - but not running!

•  If the "Registry Installation" version was previously installed that must first be removed by using the "Control Panel"->"Programs and Features" (Windows 7) display to find "Big Sur Trailmap", then right-clicking "Uninstall"

•  The Garmin map installation folder, which varies for different Windows versions, must be found.  It should have been created by the BaseCamp installation process - here is some guidance:
       Windows 7 & ?10?C:\ProgramData\Garmin\Maps

•  The downloaded "Garmin Map Install", "" (a zip format file) must be "unzipped" - sometimes Windows Explorer will automatically display the "BigSurTrailmap...gmap" folder file within the zip file, sometimes you must double-click or right-click on the file icon to obtain the "BigSurTrailmap...gmap" folder file within

•  That "BigSurTrailmap...gmap" folder file should be copied into the Garmin map installation folder.  The trailmap will then appear as a background map selection in BaseCamp when next started.  Note that this map will not appear in the "Control Panel"->"Programs and Features" (Windows 7) display and cannot be uninstalled in that fashion (since it does not use the Windows Registry). 

•  Note: you can uninstall the Big Sur Trailmap by simply deleting the installed "BigSurTrailmap....gmap" folder or (on a Mac) running the Garmin MapManager program. 


On GPS "Map" page, choose:
MenuSetup MapSelect MapBig Sur TrailmapEnable


Lines:  Five different trail/road lines are displayed: trails (green+white), use trails (orange+black), dirt gated (red+white) and ungated (red) roads, and paved roads (gray).  Trail and road lines are non-solid so they cannot be confused with user tracks on the GPS, using colors similar to those on the on-line Big Sur Trailmap.  The trail/road name is displayed when the map pointer is over it. 

Icons:  POI (Point of Interest) icons identical to the on-line Big Sur Trailmap (Legend).  icons mark stream crossings on trails which cross the same stream multiple times (e.g., the Carmel River Trail crosses the Carmel River 27 times), since knowing whether the next crossing is near can be useful.  But the icon must be small since if larger would show only a single icon at close-together crossings, negating their usefulness.  The icon name is displayed when the map pointer is over it. 

Search:  POI names can be found using the Garmin "Find"/"Where To" feature, either alphabetically or by category.  For the latter, they are "Geographic Points" with subcategories "Manmade Places" [camps, use camps, campgrounds] or "Water Features" [water sources, waterfalls] or "Land Features" [summits].  Also, trailheads and roadends are listed under "Geographic Points - Land Features"Warning: if another map is also loaded, such as Garmin's "Topo24K", a search will also find its features, which may have the name of a Trailmap feature but be incorrectly located, even if that map is "disabled"

Zoom Levels:  Not all features are displayed at all zoom levels, and this behavior can be changed by GPS setup options (but does not seem to work exactly the same on different GPSes).  So far as I can tell, the trail/usetrail/road lines are always displayed, but the contour lines only appear at smaller scales.  Different icons also appear only at smaller scales, but different icons can appear/disappear at different zoom levels. 

Labels:  Both the lines and icons have names, which can be displayed by moving the map pointer over the line/icon.  In addition, the trails/usetrails/roads have their name automatically displayed on the map at intervals (though that can be turned off if desired - see below).  To save space I've used abbreviations, which can be a bit cryptic.  Unfortunately, the GPS can change my letter capitalization, so "VDC" may become "Vdc".

User control:  The levels at which icons appear/disappear and the label text size can be controlled under "Setup""Map" with then further menus depending upon the GPS (e.g. "Advanced Map Setup" on the Oregon and GPSMAP62) which control the "Zoom Levels", "Detail Level", and "Text Size". I'm not really sure how all these work or interact with each other.  I do know that a "trail" and "use trail" are considered "streets", so if their persistent map labels bothers you, you can turn off "street labels" - but that does not affect the "roads", for which the labels remain in place! 

Contour and stream lines [for "With Topo" files]:  Contour lines are displayed at 40-ft elevation intervals.  These use terrain data comparable to a 1:24000 quadrangle map, so cannot show small-scale ridges and gullies.  The elevation is displayed when the map pointer is over a contour line.  Blue lines depict streams, with intermittent/perennial streams being thin/thick.  Stream location data is not as accurate as the topographic data (it is based on 1:100000 maps) - if the topography shows a gully but the depicted stream is displaced from that gully then likely the actual stream location is in the gully.

Vehicular roads:  The Big Sur Trailmap is intended for hiking, hence the only roads displayed are those which might be used as connectors between trails or for trailhead access.  For the "sans topography" version, another map loaded onto your GPS can provide additional roads since such will be displayed through the trailmap's transparent background (but it may also display roads/trails/etc which do not actually exist!). 

Trailhead/Roadhead POIs:  To provide a greater variety of destination locations, I've created searchable POIs for each trailhead and road end with names ala "Abbreviated Name N/E", with the N/E tail indicating that this trailhead (roadhead) lies North and East of the other one, which would be "Abbreviated Name S/W".  These trailhead POIs are displayed as a small black pushpin icon on the map when zoomed in at high map resolutions, in addition to the usual on-line Trailmap icons.  To keep them from cluttering the "Geographic Points - Manmade Places" POI category which lists camp POIs, I've created them under "Geographic Points - Land Features"

Routeable trails: 
    Trails and roads are routeable (except for "historic"/"lost" trails), meaning that within the map coverage area you can can choose a destination (for example by selecting any point along a trail or by a "Find" or "Go To" of a POI) and then select "Go" to have the shortest along-trail route to that point be calculated and displayed.  Routing works in BaseCamp as well as on the GPS itself. 
    But you should be able to find your way hiking without needing a GPS to tell you how to get there!  The main reason for this capability is to display the along-trail distance to a destination as you hike along, instead of the straight-line distance produced by direct "Off Trail" routing. 
    For this feature to work your GPS's routing options must be set to "Follow Roads", i.e. not to "Direct" or "Off Trail"
Routing details
   Automobile "Activity" ⇒ exclude use trails
   Pedestrian "Activity" ⇒ include use trails

Recent Garmin changes have forced the following non-intuitive changes:
    Setting your "Setup""Routing""Calculation Method"  "Activity" to "Automobile"/"Cycling" will now route along roads and trails, but not along use trails - so casual hikers wishing to avoid use trails should use that "Activity" setting.  Alternatively, setting "Activity" to "Pedestrian"/"Hiking" will route along use trails.  Currently, the "Minimize Time" and "Minimize Distance" selections seemingly have no effect on my 64s and 66i model's routing - but that may change in the future.  Unfortunately, with the latest changes it is no longer possible to prevent routing along roads - roads and trails are equivalent, routing-wise. 
Non-shortest route
   For a route which is not the shortest between two points, you must use the GPS "Route Planner" to manually create the route - this is a PITA on the GPS, due to the cumbersome cursor movement process, but can be done.  It's much easier to create the route on your PC using BaseCamp, since the mouse can select points, then transfer it to the GPS. 
   If your "Maps Configure" is set to use multiple maps, notably a OSM map in addition to Big Sur Trailmap, the routing used may not be the Big Sur Trailmap routing, even if the Big Sur Trailmap is displayed - so if the routing appears incorrect, disable other maps! 
    For years Garmin's GPS routing allowed inclusion or exclusion of roads, trails, and use trails.  But recent changes have limited the options, so I can now only include or exclude one of those.  Since the map is primarily for hiking, and since I want to provide along-trail distances along all routes, I decided to include/exclude use trails. 
    So you cannot now route only along roads or avoid routing along roads - roads and trails are now indistinguishable routing-wise.  So if a road happens to be the shortest distance between your start and end points, you must first route to an intermediate point and upon reaching it route to the end point.  Alternatively, you can create a Garmin "Route" giving the start and end points as well as an intermediate point that will force the route to follow your trail - it's a PITA, but will then give distances, etc. along the entire route. 
    Hopefully Garmin will later allow "Cycling" activity to differ from "Automobile", so I can revert to providing route options differentiating between roads and trails. 


BaseCamp -- and the older MapSource, which some still use --
are Garmin programs which can interact with a Garmin GPS and display GPX waypoint/track data - they only run on Windows and Mac PCs.  The Big Sur Trailmap can be displayed as a background map after the installation procedure described here
    I am not going to treat BaseCamp software use - you can find a brief tutorial at the following link:  How To Load Maps On My Garmin GPS Unit (which includes instructions for a Mac).  But note that if using BaseCamp "Install Maps" to update a previously installed Big Sur Trailmap on your GPS you will likely need to do in two steps, first using "Install Maps" to remove the existing GPS map and then using "Install Maps" to add the updated map. 

Viking desktop GPS data editor and analyzer
A non-Garmin desktop GPX data viewer which can also interact with your GPS similarly to Garmin's BaseCamp - it runs on both Windows and Linux PCs.  To use the Big Sur Trailmap tiles as a background map, you must (after installing the Viking program!) install map setup file maps.xml - the exact location depends upon where your system installs Viking, but typically should be in directory "C:\Documents and Settings\username\.viking\" for Windows installations and "/home/username/.viking/" for Linux installations.  To display the Big Sur Trailmap as a background map, under "Layer", "New Map Layer", select "Big Sur Trailmap" (usually the bottom item in the map list) and use its default options, which should have the "Autodownload maps" box checked.  I have tested version 1.4 and 1.6 in Linux, not in Windows.  (Note: Viking uses the Big Sur Trailmap tiles described further at , not the Garmin-format map files described above, so does not have the routing capability of BaseCamp). 

If you can provide corrections or additions to this webpage, or if you have an opinion regarding this Garmin-format version and how it might be improved, post to the Trailmap forum.