The expedition was sponsored by National Geographic and apparel maker the North Face, with support from Montana State University.

WSJ: Mayo Clinic Researchers on Everest Study High Altitude's Effects on the Body

It was day two of our voyage aboard the National Geographic Endeavor, a 96-passenger expedition ship that sails 10-day itineraries around the 13 major, and many smaller, islands that span the Equator.

BBC: The Gal��pagos Islands, a land untouched

Previously, National Geographic Traveler included a 300-mile (483km) sea kayaking expedition along Scotland's west coast as the only UK entry in its list of 50 Tours of a Lifetime.

BBC: On the West Highland Way