• Bon Tempe Lake (map)
  • Fairfax, CA, 94930
  • United States

2026 Nav-X GPS MAP TREK #3 @ Mt. tamalpais WATERSHED

Quick Info

  • Date: Sunday, 1 March to Thursday, 30 April

  • Location: Mt. Tamalpais Watershed, Fairfax, CA

  • Courses: 3hr & 6hr GPS Map Trek

  • Prices: $20 (3hr) & $27 (6hr); Juniors 50% off, Club members $4 off, Children 12 & under FREE; also see below for pre-printed map options.

  • Map Handout: Sunday, March 22 at 10am (tentative)

REGISTER

Notes about registration: An Orienteering USA membership is not required: instead, use the Enter Data Manually option instead.

If you are part of a team, everyone on your team (over 12 years of age) must register separately.

INTRODUCTION

  • We have set up a course with xx checkpoints on a new map in the Mt. Tamalpais Watershed / Bon Tempe Lake area near Fairfax, CA. Get as many checkpoints as you can in either 3 or 6 hours using the Smartphone app named “MapRun” to record your visit to each checkpoint based on your GPS position.

  • The competitive window for this event is March 1 - April 30, 2026. Results during this time period will be included in the official results and accrue Nav-X series points but the course will still be available on MapRun until Dec 1, 2026, after which it will move to the archived courses. Upon registration, you will receive (1) registration confirmation, (2) within 24 hours, a separate email with links to map documents. 

  • Pre-printed maps are available by mail for $10. Maps will generally be mailed to arrive in your mailbox within 7 days of registering. For Mt. Tamalpais Watershed, the deadline for ordering pre-printed maps is April 1.

  • Our suggested race time is Sunday, March 22 at 10am. We will have a Nav-X team member there to hand out pre-printed maps if you register for this option ($6) by March 16. Since this is not an official event, there will be no signage so just meet the Nav-X staff member at the start triangle. The maps will be available from 9:30 - 10:30am.

IMPORTANT SAFETY NOTES

  • YOU ARE DOING THIS AT YOUR OWN RISK - WE TAKE NO RESPONSIBILITY FOR ANY INJURIES OR DEATH.  HAZARDS INCLUDE STEEP HILLS, LOOSE ROCKS, CLIFFS, OCCASIONAL DENSE AND SHARP BRUSH, POISON OAK AND TICKS.

  • CELL COVERAGE - Unfortunately, there is very little cell phone coverage in most locations on the map. I was only able to get a signal on Rocky Ridge, the ridge south of Bon Tempe Lake.

  • WHISTLE - Due to the self-serve format, you may be completely on your own when you run your course. Be aware of this! You should bring a whistle in case of an emergency.  

  • WATER - There is no water available at the start/finish but there are water taps at the Lake Lagunitas parking lot (at the end of the paved road). It is recommended to bring all the water you need on the course with you.

  • POISON OAK -  on the lower end of Bay Area parks.

  • TICKS - are present and were seen during course setting.

EVENT INFORMATION

  • MAPRUN - Please see this page for instructions on how to use the MapRun smartphone app.  It’s important that you load the course while you still have Internet service.  Search for “2026 Nav -X GPS Map Trek Mt. Tamalpais” and pick the right course (3 hr or 6 hr). Or you can click one of the links provided above to load the course.

  • DIRECTIONS TO START: The start/finish is located closest to this parking spot. (The start/finish is just far enough from the parking area so that you don’t accidentally trigger it when you park). Follow highway 101 north or south to exit 452, downtown San Rafael. Follow 3rd St west, which becomes 2nd St, then 4th St, then Red Hill Ave. After 2.2 miles from the freeway, turn right onto Sir Francis Drake Blvd. After 1.7 miles, turn left on to Pacheco St and then an immediate right onto Broadway and then immediate left onto Bolinas Rd. Follow for 1.5 miles, and then turn left onto Sky Oaks Rd at the sign for Lake Lagunitas. After 0.5 miles, stop at the parking area just past the entrance kiosk on the right for the automated pay stations. 

  • PARKING  - Day use parking passes ($8) can be purchased from the automated pay station located at the Sky Oaks Headquarters, just past the entrance kiosk. The automated pay station accepts credit cards and $1, $5 and $10 bills. Exact payment is recommended because the automated pay stations cannot make change. Coins and $20 bills are not accepted at the pay station. Put the parking permit on your dashboard and continue on Sky Oaks Rd for 0.3 miles and bear right onto Bon Tempe Rd. (dirt). Continue 0.4 miles to the parking lot at Bon Tempe dam. The parking here can be full on weekend afternoons so it’s best to arrive early.

  • BATHROOMS - There is a portapotty just off the parking lot near the start but no water. There are also bathrooms and water fountains at the Lake Lagunitas parking lot at the end of Sky Oaks Road (paved).

  • GEAR RECOMMENDATION - We recommend participants bring the following:

    • Smartphone - goes without saying since we are using an app for timing

    • Compass

    • Long pants or at least gaiters for the tall grass, brush, and poison oak

    • Snacks & Water, especially if you are on the long course

    • Whistle for safety

  • TRASH - While on the course, practice Leave No Trace (LNT) - bring all trash back to the parking area.

  • BE DISCREET - We don’t have a permit so try not to be too noticeable when entering or exiting off-trail areas.

MAP & COURSE NOTES

  • VENUE - The Mt. Tamalpais Watershed area is one of the most beautiful in the Bay Area, consisting of stunning redwood forests and lakes. The mapped area includes the existing BAOC Bon Tempe orienteering map in the north and east, including the Pilot Knob addition, Rocky Ridge in the south, and Azalea Hill in the west.

  • PROHIBITED AREAS: Residences, maintenance yards, golf course, etc. Observe the restricted areas (hashed purple lines on map). In particular, the top of Azalea Hill and the creek between Azalea Hill and Bon Tempe Road are prohibited.

  • TERRAIN - Mostly forested with some open grassland and manzanita areas. Redwood trees are fairly abundant in the area. The top of Rocky Ridge and Azalea Hills have an extensive area of open land with manzanita bushes of varying height. These bushes  are mostly mapped as dark green (fight) but in fact, you can usually find passages through it. If you get stuck in a dead end, generally you can back out and find a clearer path through nearby. The yellow color in these areas is not grassland like the rest of the map, but rather shorter manzanita bushes which despite having great visibility is still tough to get through.

  • MAP - The overall map was created in Aug and Sept 2024. It has 5 meter contours, vegetation density (3 shades of green), cliffs, and water features based on high quality LIDAR data from 2018-2019. BAOC’s Bon Tempe orienteering map (most recently updated in 2025) is incorporated into the overall map. Roads, trails, fences, and other features were added using Google aerial imagery, Strava Global heatmap, and the adventure racing map used for the Bone Tempest events. Other features were added and adjusted during field checking but the map lacks most orienteering-level detail such as boulders, knolls, rootstocks, single trees, etc.. (except of course for the area covered by the BAOC orienteering map). On the orienteering map, stands of redwood trees are shown with a solid thin black line, rather than the dotted veg boundary symbol so that they are more legible. The narrow ride symbol is used to denote an old road grade. These are often overgrown with no trail but are still useful for navigation. Also note that the autogenerated vegetation density from the Lidar data in the newly mapped areas are shown by somewhat different colors than the corresponding areas in the existing orienteering map. The autoveg color for rough open land is a darker yellow and the greens are tinted yellow compared to the greens of the orienteering map. Unfortunately, I can’t edit the colors of the auto vegetation.

  • COURSE - The course was designed by Andrew Peterson. There are xx checkpoints varying in point value from 30 to 100 points. The approximate straight-line distance to get them all is about xx km. Generally, higher value checkpoints are farther from the start, harder to find, or some combination of both.

  • START - The start area is shown on your map as a triangle and is on a trail just east of the parking lot. Do not approach the start until you are ready to go! Your GPS device will start you automatically and alert you by beeping once you are within ~15 meters of the spot. 

  • SCORING:  Just like our other events, each checkpoint has a point value reflecting the difficulty (higher point value for tougher checkpoints).  The point value is the “10 part” of the checkpoint code.  Examples:  33 = 30 points, 50 = 50 points, 88 = 80 points, etc. Late penalty is 10 points per minute or any part of a minute (1:01 late = -20 pts)

  • MARKERS - All checkpoints are marked with biodegradable ORANGE flagging with “Nav-X” written on it. Be aware though that as time goes by, animals and hikers may remove some of the flagging, so it is not guaranteed to be present. The start/finish does not have flagging because it is in a public place.

  • FINISH - the finish is marked on your map with a double circle and is located at the same place as the start. When you are within ~15 meters of the spot, your GPS device will register a finish. Do not approach the finish until you are ready to end your course. (Depending on the device, it may be possible to continue the course after this, for example if you approached the finish spot by accident. However, this might not work for you, so we recommend you don’t go near the finish until you are done.) Remember to upload your result after you finish (if it doesn’t happen automatically).

  • MAP PRINTING - We are providing a Zip file with the map documents in PDF format within 24 hrs of registration. The text checkpoint descriptions are on the map. You will need to print your own maps or choose one of the 2 pre-printed map options. For $10, you can have a map mailed to your address (allow 7 days for maps to arrive); this option is available until March. 31 on the registration page. For $6, you can pick up a map at the in-person meetup on Sunday, March 22 from 9:30 am- 10:30am; this option is available until March 16.

If you want to report any problems with the course, please email info@navxchallenge.com.

Thanks for reading, and have fun! - Andrew, Bill, and the Nav-X team