Bu Tinah Island, United Arab EmiratesShe was standing on the gunwale in a wetsuit, clinging to an awning with one gloved palm. Then a dark shape emerged and zipped through the emerald water.

Jimena Rodriguez, a marine biologist with the Emirates Wildlife Society-WWF in the United Arab Emirates, bent her knees so she bobbed with the swells as the boat cut out across a sun-baked shoal, 50 miles into the Persian Gulf from Abu Dhabi. Behind her, the boat's captain, scientist Nicolas Pilcher, muttered, "Wait ... wait ... wait." Then he barked: "Now!"

Rodriguez launched herself from the deck, popping up from the water seconds later holding an enormous green sea turtle by the carpace. That afternoon, her fellow researchers would check its health, measure it,