"60 MINUTES" CAMERAS CAPTURE RARE AND ENDANGERED FISH AND CORAL ON A PRISTINE CUBAN REEF - SUNDAY ON CBS

Fifty miles off the shores of Cuba lies one of the world's healthiest coral reefs, an undersea Eden full of rare and endangered species. Anderson Cooper and 60 MINUTES cameras take viewers on an underwater adventure to this colorful world that could disappear someday if mankind isn't more careful. Cooper's story about Cuba's "Gardens of the Queen" reef will be broadcast on 60 MINUTES, Sunday, Dec. 18 (7:00-8:00 PM, ET/PT) on the CBS Television Network.

One hundred feet deep in crystal clear Caribbean waters, with sharks angling by, neon-colored fish schooling, and a 200-lb. Goliath grouper hovering a few feet away, Cooper interviews marine biologist David Guggenheim of the Ocean Foundation in Washington, D.C., using special scuba masks that permit them to talk underwater. "Do you ever see groupers this big elsewhere," says Cooper, bubbles rising from his regulator valve. "Never, never in my life. It's a critically endangered species," says Guggenheim, who is familiar with many of the world's ocean reefs. Watch an excerpt.

Reflecting after one of their dives, Guggenheim tells Anderson Cooper he is impressed with what he saw on the reef, which the Cuban government has protected from commercial fishing and development. "The corals are healthy. The fish are healthy and abundant. There are predators here, large sharks," Guggenheim says, noting that sharks "are a very important part of the ecosystem and we've kind of forgotten that, because we've taken about 90 percent of sharks out of the world's oceans over the last 50 years."

Just like the large sharks and the groupers they sustain, coral reefs themselves are in danger. Guggenheim shows footage of a reef in Veracruz, Mexico, he visited, where he says he found 90 percent of the reef dead. Scientists say coral is succumbing to a complex combination of environmental factors including pollution, agricultural run-off, coastal development, over-fishing and rising ocean temperatures, which researchers believe is causing a phenomenon called "bleaching," that causes the coral to turn white and sometimes die.

There has been a little bleaching at "The Gardens of the Queen," but the coral tends to recover after a few months, leading scientists to wonder whether there is something about this area that might provide clues to saving or regenerating the rest of the oceans' reefs, says Guggenheim. "Maybe it's because this ecosystem is being protected, it's got a leg up on other ecosystems around the world that are being heavily fished and heavily impacted by pollution, so that makes it more resilient."