Here's a picture showing you the 4 different steps i used:
-first I poured a whitey-yellow tinted resin at the bottom of the mould, this is to create the waves;
-after the resin begins to set, i took a brush and procided to stretch the stuff along the borders of the moulds so that it produces some kind of jelly;
-then some transparent blue to create the bulk of the sea
-then a final darker and opaque resin layer to '"seal'" the whole sea.
Now let's wait a full night to see how it goes..