• Kenny Broad
National Geographic Emerging Explorer Kenny Broad goes where few go–deep into caves and blue holes in the Bahamas. Broad tells Boyd it is extremely dangerous to dive hundreds of feet into dark caves. But what’s really exciting is what he’s finding in these remote locations.
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• Eric Yang
Boyd tests his geographic knowledge against Eric Yang, the 13-year-old winner of this year’s National Geographic Bee!
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• Andrew Johnston
Andrew Johnston is a geographer at the National Air and Space Museum and co-author of the new book, Smithsonian Atlas of Space Exploration. Johnston joins Boyd to talk about 50 years of American space exploration.
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• Gary McKechnie
Gary McKechnie, author of USA 101: A Guide to America’s Iconic Places, Events and Festivals joins Boyd to suggest summer vacation destinations.
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• J. Maarten Troost
J. Maarten Troost spent months traveling through China in an attempt to understand what he calls the world's most mystifying nation. Troost chronicles his adventure in the new book, Planet China, which he and Boyd discuss.
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• Kerry Kriger
Frogs are facing the deadliest disease ever seen on the face of the planet. Nearly one-third of the world’s amphibian species are threatened with extinction. National Geographic Grantee Dr. Kerry Kriger started the Save The Frogs foundation in order to fight this trend.
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• Eric Whan
Everyone wants to be green now. But do you really know how your personal choices are adding up? What about the choices of your fellow citizens? Eric Whan, director of the National Geographic Greendex survey, joins Boyd to answer those very questions.
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• Robert Earle Howells
Looking for an adventure close to home? National Geographic Adventure magazine has some suggestions. Robert Earle Howells contributed to a list of the "50 Best American Adventures" in the May issue of the magazine. He and Boyd talk about biking the continental divide and kayaking the coast of Hawaii.
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• Notes
Boyd says even a routine scuba dive can go horribly wrong if you don’t maintain your equipment and follow procedures carefully.