I need ideas for this... anything would help! Thanks!

All I can think of is making an octopus out of gumpaste or fondant. Then you can have it holding a rattle in one hand (tentacle?), a bottle in another, maybe a pacifier. Then you could do the shells, seaweed, and fish to get the whole under the sea look.

hi ya well when i read your post i automatically thought of water babies, you could do decorate the sides of the cake like under the sea with some fish, starfish, shells, octopi or jelly fish, but add the water babies as well and if you use pastel colours on the cake it will keep it looking like a babies themed cake....if you know what i mean. hope this helps. libs