There is a stone quarry within the boundary of Coyote Hills Regional Park. There is a road from Paseo Padre Parkway that will take you to the quarry. I think the quarry is being abandoned and the area will eventually become part of the park. You can see part of the quarry, i.e., a giant hole in the rock, from the Apay Way trail and overpass (above Hwy. 84) that connects Don Edwards Fish and Wildlife Refuge and Coyote Hills. The shape of the accummulated water in the quarry is in the shape of South America. It will be interesting to see how this land is brought back to the park. Given this gian hole I can imagine many fun games for children.