What are fun things to do on huge concrete rocks?

go swimming and then lay in the sun of the concrete to get warm and then go back into the water. hike to the headwaters and float down the ravine on floaties until you come to that spot, then stop. Get some wood and an air mattress, tell your parents you are sleeping at a friends, and go out there and have a bon fire with friends! --there is so much to utilize that place.