[ZenGum]

I've been wondering if you put any edible features in the jelly. I think that snakes (do you have that kind of lolly there?) would work, and there are probably more nautical shape edibles.

And for a diving/swimming theme jelly diorama you could use two layers of different coloured jelly, a pale yellow one for air and a blue one for water, and have a diver/swimmer going from one to the other.