MarcoPolo Ocean (MarcoPolo, 2014; iOS only) — in the same series as MarcoPolo Arctic — introduces young children to an ocean biome. A blue sea with gentle waves appears on the main screen as vaguely Caribbean-sounding background music plays. Before beginning, you can orient yourself by investigating underwater, looking at some fish, bobbing the buoy, etc. The fish icon at the bottom left allows you to add some cute-looking creatures in scuba gear or additional fish to the scene, or to sprinkle fish food into the water.

When you touch the puzzle piece icon at the top right, six items appear at the top of the screen: coral, an octopus, a fish, an orca, a boat, and a submarine. Select one to begin.

If you pick the fish, the narrator says: "A herring is a small silvery fish that eats plankton. Let's build a herring." Fish body parts appear one by one at the top right; drag them to the proper spot on the body. Most of the parts are identified by name, with more info provided about some of them: "Gills: fish use their gills to breathe underwater." Add more and more herring to a school as the narrator supplies some additional facts ("Some herring are small enough to fit in your hand"). Once the herring are all placed, other fish can be added to the scene: tiger shark, barracuda, angler fish, etc. If you select the orca icon from the main screen, the focus is sea mammals; the coral is a reef; the boat and submarine (called a submersible) tell more about those types of vehicles.



Each time you complete a category, there's more to explore on the main screen. After completing the fish section, scroll down deeper into the water to the midnight zone — complete with sea stars and jellyfish — and the soundtrack shifts to dramatic new-age-y music. Completing the mammals category lets you play with a dolphin jumping and making the orca spout water from its blowhole, etc.



The maritime learning is somewhat scattershot: the additional facts seem a bit random, for example, and the shape-matching isn't totally precise. But the app is useful and entertaining for young kids interested broadly in sea life and undersea exploration. Dive in!

Available for iPhone, iPad, and iPod touch (requires iOS 7.0 or later); $2.99. Recommended for preschool and primary users.