On the 15-minute flight from Nassau to Andros, you pass over an enigmatic stretch of sea known as the Tongue of the Ocean, which even from a few thousand feet in the air seems to be an unusually profound shade of blue. Over a mile deep, this famous trench helps to account for the extraordinary fertility of the region’s marine life, which attracts scuba divers and fishermen from all over the world.

Andros is the least developed of the Bahamian islands and the contrast with the high-rise hotels and the mega cruise ships of Nassau could scarcely be more extreme. A hundred miles long and a maximum of 40 miles wide, it has a total land area larger than the rest of the Bahamas combined. Although regarded as one island, Andros is actually an archipelago, consisting of hundreds of cays connected by mangrove-lined estuaries and tidal swamps. Three main islands — North Andros, Mangrove Cay and South Andros — are separated by “bights” that connect the east and west coasts. The interior is almost impenetrable and is said to contain one of the largest tracts of unexplored land in North America. A local population of about 8,000 lives chiefly along the east coast, where a succession of small communities is linked by a single atrocious road.

Tiamo Resort

One of National Geographic’s “Unique Lodges of the World,” Tiamo was designed to coexist with its pristine natural surroundings. A decade ago, its construction was completed without the use of large machines, and the necessary land was cleared instead by machete. There is no road access to the resort, and all supplies must arrive by sea. Today, the property’s 11 villas and two guest rooms are buried in thick indigenous vegetation. As we moored alongside the jetty, I gazed down into the water. It was teeming with fairly sizable fish, including a small lemon shark, 3 or 4 feet long, which cruised among the shoals in search of an unwary straggler.