Skydiving. The number of people that sign up for the training is tiny and only about ten percent of them make it through ground school, all the tested jumps, the written test and the oral test to get licensed.
But, it is surprisingly addictive and fun.
It also is a small enough community that when I say my instructor died this summer, I bet that others funjumpers reading this knew him or of him.
I miss you Frog.
Goddammit.