You can make this cake with any size or shape cake you desire or have pans for. I made to 10" round cakes and layered them on each other, then I cut the top layer down about 1" and scooped out the cake. Next I did a fast set Jello, in green cuz I couldn't find blue. Poured it into the cake and then since I didn't want to have a slimy looking pool I added some drops of blue food coloring to give it some moving water effect. You can't really see it in the pictures though. Next it went into the fridge overnight (but you don't have to wait that long).