A manta ray channels plankton-rich water through its mouth near Hanifaru, one of the Indian Ocean islands that make up the Maldives, in an undated photo.
Hundreds of giant fish converge in Hanifaru Bay from May through November, when the lunar tide sucks krill and plankton to the surface, giving rays an all-you-can-eat buffet.
(Read about the manta ray feeding frenzy in National Geographic magazine, or see more photographs.)
In June 2009 the Maldives created three new marine protected areas that include Hanifaru and other crucial feeding areas for mantas and whale sharks, the world's largest fish (whale shark pictures, facts, and more).
Fishing, boat speeds, and waste disposal will be regulated. The new sanctuaries, however, will allow some diving and snorkeling—a healthy tourist trade may provide alternative livelihoods for fishers, experts say.
"The government is committed to protecting and preserving the Maldives' exceptional biodiversity," Maldives Environment Minister Mohamed Aslam said in a statement.
"The marine environment is the bedrock of our economy, supporting our largest industries, tourism and fisheries."
(The National Geographic Society owns National Geographic magazine and National Geographic News.)
—Photograph by Thomas P. Peschak, NGS Image Collection