The bottom tier of this Homemade Underwater Birthday Cake Design was baked in a cheesecake spring pan, the top was baked in a smaller cheesecake spring pan (not sure of dimensions). The bottom layer and all fish, dolphins, whale tail, and plants are made from premade fondant which is used neon food coloring from the grocery store. The fondant used to cover bottom tier was a dark blue not completely mixed with a lighter blue to give a tie dye look. The top layer was made from marshmallow fondant (we ran out of premade) and colored with light blue color mixed with plain white fondant. Had some trouble laying the MM fondant on top tier (it was our first time using homemade fondant) so we got a bubble or roll on top, but we decided it was a wave on top of ocean.
The dolphins, fish, and plants were very easy, I just youtubed some videos ("how to make a jumping dolphin by Mystikal Mischief", for the fish, I just youtubed "how to make fish from clay", clay is the same concept as fondant. We covered the cake stand with brown sugar to look like sand and added some cookie cutter starfish. The fish were a little heavy, so we used toothpicks to keep them in place on the cake. The whale tail was made by hand without a youtube video- basically I used white fondant to made a cone shape for the body of the tail, then separately molded the actual tail. I used water as glue to hold the 2 pieces together, then covered the fron side with black fondant. The black fondant also helped reinforce the "glue".
The only issue we had was the whale tail wasn't completely dry in time for the party, but we added it anyways. The tail did droop a bit, but it still looked great! Enjoy!!