Photo gallery image (click to enlarge)

“Corona” Course #2 at Black Diamond Mines

Black Diamond Mines Regional Preserve

Dates: February 21, 2021 to ??
Location: Antioch, CA
Course Setter:
Type: Training; Tough course optionally using the O-range app for Garmin watches

General Notes

I set a new course at Black Diamond Mines Regional Preserve (​—​5.3 km, 21 controls, with a lot of climb and gnarly vegetation in some spots. It reuses some locations from the previous Corona course, but all the legs are different. There are also new controls.

The upper parking lot is open, so it is more manageable.

You can find the course on Look for "Black Diamond Mines Training" in the Public Courses. Click on the line, then click on the circle at the right on the line "Training, 21 controls, 5.3 km", then select "Open map".

If you have a Garmin watch that supports apps, you can download the o-range app (, and you'll get a ping when you are near a control.

You don't need to use the GPS function​—​simply download and print the map PDF and use it by itself.

I'm making this available just for fun, so no sign-up sheet or anything.


Coordinates for the park entrance are 37.9712023,-121.8627757.

Enjoy 😊

François Léonard
(February 21, 2021)