From Sea to Sky: Submarines That Fly

Guillemots and gannets do it. Cormorants and kingfishers do it. Even the tiny insect-eating dipper does it. And if a plan by the Pentagon's Defense Advanced Research Projects Agency (DARPA) succeeds, a remarkable airplane may one day do it too.

Plunge beneath the waves to stalk its prey, before re-emerging to fly home.

http://gizmodo.com/5579644/from-sea-to-sky-submarines-that-fly