Your three-and-a-half-hour flight from Colombo, Sri Lanka, to Bangkok, Thailand, was uneventful until the captain’s voice calmly announced, “This is the captain, brace for impact.” The flight attendants began their chant, “Brace, brace, brace! Heads down, stay down! Brace, brace, brace!” The chant ended as screams filled the cabin, mingling with the roar of metal tearing and the rush of seawater. As you regain consciousness, you have only moments to escape the plane. You hope the island you glimpsed is nearby and that it is not North Sentinel Island, where travel is forbidden and the inhabitants are notoriously unfriendly.