Divers have got lost underwater and you, with your yellow submarine, go in search of them. This search is not without risk: as soon as a laser beam hits you, game's over! Most black rocks are hard, but each level also contains a secret space that you can reach by navigating 'through' the rocks: this is how you can reach the secret spaces. You can use the white 'resize' surfaces to become smaller or bigger so that you can access places out of reach. Try to grab three stars in each level to unlock bonus levels!
http://www.gamevideo4u.com/hero-in-the-ocean-walkthrough-all-levels-all-secrets/ Walkthrough video of Hero in the Ocean!
Arrow keys = move around.
space bar = next level.