Mexican DPS Summits -- Garmin-Compatible GPS Maps

Harlan W S
Aug 19, 2013

There are four Desert Peak Section (DPS) summits in Mexico: Picacho del Diablo, Pico Risco, Cerro Pescadores, and Cerro Pinacate.  Before our recent trip to Picacho del Diablo, we attempted to get garmin-compatible topographic maps.  There are two commercial vendors, who will sell maps for the entire country; those maps are great for many of the most popular destinations.  However, in the areas around the
four DPS summits, the commercial maps are either misregistered (the contour lines are shifted 50-200 feet), or the secondary roads tend to be inaccurate. Hence I set out to make topo maps from freely-available
(USGS) sources, and to correct the misregistration and add roads from aerial photos.  

These maps were made solely for climbs of the four Mexican DPS summits; they do not contain details of the big cities.  All have embedded hiking routes; for Picacho del Diablo and Cerro Pescadores, the hiking routes are based on actual gps tracks. For Pico Risco, the hiking track is based on the DPS map.  For Cerro Pinacate, the "route" consists mainly of the waypoints available at, with a hypothetical path around the lava flows.  The dirt roads were picked off aerial photographs. Registration corrections were vexing; I have not been able to find reliable locations for the Mexican benchmarks (monuments, often on peaks), so I resorted to reported GPS data and other information. For Picacho del Diablo, we had our own tracks and other waypoint measurements for the peak; steep cliffs on the ocean, and Y-junctions in deep gorges, acted as well-defined features to match with contours produced from the digital elevation models (DEMs).   For Risco, the contours were shifted so the  correspondence between landmarks on aerial photos, and the valleys, was decent. For Pinacate, gps points for the peak top, and the edges of deep craters, gave some confidence that the contour lines were properly re-registered with the features on the aerial views.  Pescadores is problematical; the summit is fairly broad, and the summit sign-in is apparently not at the highest point.  I tried to reach a correspondence between the obvious ridges visible in aerials, with the contour maps, and a gps track that followed a ridge.

(All DEM data are from the USGS NED server; 1 arc-second data for Diablo, and (supposedly) 1/3 arc-second for the other three summits. Most of the 1/3 arc-second data appears to be derived from over-sampled 1 arc-second data.)

It wasn't until I was finishing the last map (Pinacate) that I realized all the USGS DEM data for Mexico had a curious chracateristric that caused bizarre contours in nearly flat areas.  The maps for Diablo and Risco Pescadores still have these bizarre comtours (but not in areas one must hike), and I may update those maps in the future.  I have solved the problem with a data analysis post-processor; while that post-processor is easy enough to apply to the other DEM data, it would require me to remake the maps completely.

I was forced to make the Risco map "trasparent," else it would never show on the GPS itself; I suspect there is some odd flaw in the Garmin basemap in this area. Unfortunately this means that in BaseCamp (NOT on the unit), you may see some contours from Garmin's incredicly coarse basemap showing through.  I repeat, these rogue contours will not show up on the actual GPS display.

These maps are made available without any gurantees whatsoever; use them at your own risk. There are three maps: Diablo, Risco-Pescadores, and Pinacate.  If you have a PC, and an "older" Garmin mapping unit (e.g. 60csx), you can use the self-installing maps here, here and here. You MUST have completed the installation of BaseCamp or MapSource (latest version) before running these executables.  You can use these self-installing executables with a PC (Windows machine) and a newer Garmin as well. But the main advantage of self-installing maps is for older units; the older units will accept only one image file. After running the self-installing files you will be able to use MapSource/Basecamp to bundle the Mexican maps with other maps you have installed on the PC, and send one large image (img file) to the GPS

If you have a Mac or PC with  a newer Garmin GPS (e.g. 62sc, Oregon, Colorado), you can download the zipped img files here.  Unzip the file, then drop the desired img files directly on your SD card (in the Garmin unit); make sure you place them in the "correct" directory for that model GPS.

Region of Diablo Map.
Zoomed closeup (from GPSMapEdit)
of gps track on Diable map.
Overview of map for Pescadores (R side)
and Risco (L).
Intermediate zoom for two dirt roads into
Risco; the Mud Flat Road is not for wet
Hike into Risco, after DPS instructions.
Inytermediate zoom for east side of map
for Risco and Pescadores. Shown is drive
and hike for Pescadores, from MX rte 5.
Zoom for Pescadores.  The track is a
slight modification of Keith Christensen's
track as given on
The Pinacate map is small, but covers
the hike.  Waypoints are based on
Last part of trip to Pinacate. The "trail"
around the lava is purely hypothetical.