(CBS News) 60 Minutes cameras take you on an underwater adventure off the Cuban coast to one of the world’s most pristine and vibrant coral reefs, known as the Gardens of the Queen. Anderson Cooper scuba dives with marine biologist David Guggenheim, dodging giant groupers and sharks, to explore this increasingly rare oasis. Scientists estimate that more than 25 percent of the world’s reefs have died off and much of what’s left is at risk.