Deep-Sea Submarine by TouchyBooks is a preschooler's underwater mission to steer their submarine through various obstacles to find the sunken ship full of gold. The graphics are very cute and geared more towards younger audiences (3-7) with their bright colors and cutesy marine life.
The kids really enjoyed "steering" their submarine around the whales, fish, electric eels, and schools of fish to name a few. It was very easy for them to push the arrows to propel the submarine, and I liked that it taught them directionality as well (up, down, left, right). The interactive features were limited in that some of the marine animals would would make noise, move, or squirt ink (the giant squid); however, they didn't seem to mind because they were too interested in fighting over who got to steer the submarine next.
Deep-Sea Submarine is worth the download if you have a little one who is a fan of underwater animals.