For the dive rock we installed in the picture, we first installed a small concrete pad 6” thick reinforced with steel rebar on the inside. This gives a footing for the dive rock to rest upon, and will prevent the dive rock from settling over time. The concrete pad is under the dive rock and not visible. Then we set the dive rock on top of the footing into a bed of wet concrete so that the bottom of the dive rock adhered to the concrete footing. Then we added other boulders around the dive rock and secured them into place with concrete. These other boulders add interest and places for the children to climb upon. Good luck with your project! We'd love to see the finished project.