Not that kind of grass, shame on you!
A day at the park (http://www.youtube.com/watch?v=0A16cXE_7NQ#ws-lq-lq2-hq-vhq)
That looks like fun. I think I would be all bruised and beat up though. :) nice background music too! :)
That spot is actually really soft. It was built up using sand, then soil and sod on top, so there's no rocks in it. The tree roots stop at the top of the hill. It's a great place for a nap, too!
Looks like a blast!
and fun too