Speaking of mountain biking underground, Aaron Chase, Eric Porter, and Chris Van Dine were getting rad in Mexico recently, and built a blind drop into a sink hole in the ground. Check out how they went about building it, and what it looks like to drop into a pit in the earth:
Video: Dropping into a Cave in Mexico
By Greg Heil
Updated
Updated

Known as "MTB Greg" across the internet, I live to travel and ride new trails. My travels have taken me across the United States multiple times, and now, around the world. After serving as the Editor in Chief for Singletracks for 5 years, I'm stoked to continue contributing to this incredible community. I also write about getting outside every single day at Outside365.blog
I know this is not the same thing but have you heard of this race?
http://www.minersrevenge.com/
And this site has map and video of this race….
http://trailgenius.com/trail-genius-map/miners-revenge-1st-lap?trail=0&view=NA&time=283&fb_source=message
O.K.
I have done some crazy stuff in my day, but this is just lunacy!