Подводный мир

Manuk, a small volcanic island in Indonesia, to learn why its waters are teeming with thousands of venomous sea snakes. Also: a visit to a remote atoll in the Maldeves where manta rays gather for a few weeks every year

Bird observes bull sharks off the Mexican coast; and visits NASA's Neutral Buoyancy Lab in Houston, where astronauts train for space walking in a pool that's about half the size of a football field