A downloadable game

In a world, where fish rely on submarines to stay under water, four heroes has been set on a secret mission. The heroes are herrings and the submarine is called Seal.

They don't know the objective neither do you. 

Suddenly they where attacked by a giant squid, with a desirer to squeeze submarines.

Now the herrings must keep the submarine... afloat? unfloat?... whole. The herrings must keep the submarine whole.