The limestone rock of the Bahamas is pock-marked by blue holes–deep vertical 'caves' created by the collapse of limestone sinkholes. Over the centuries, these eroded hollows have filled with rain and seawater, creating unique aquatic ecosystems all over the Bahamas, including in this fascinating national park on Andros in the Out Islands. Many offshore sinkholes can be explored by divers, but Blue Holes National Park is the best place to explore this remarkable geological phenomenon on land–and by explore, we mean 'throw on your swimsuit and dive in'.

　　

Exploring Blue Holes National Park

Most tropical archipelagos were created by volcanic activity but the islands of the Bahamas were formed when a massive plateau of prehistoric limestone subsided into the sea. This twist of geology has created perfect conditions for the formation of blue holes, with water constantly dissolving new hollows beneath the bedrock (you'll find similar geological conditions along the cenote-filled coast of Yucatán in Mexico). Visitors to the Bahamas will find blue holes on many islands but Andros is the easiest place to get close to blue holes on land.

　　This 40,000-acre national park comprises vast tracts of Caribbean pine and coppice forest pitted with dozens of blue holes–more than 50 at the latest count, but future sinkholes are forming all the time below the surface. Trails and info boards introduce you to the flora, fauna and geology of these unusual ecosystems, but for most people, the big attraction is being able to swim in the cool waters of these idyllic-looking natural swimming holes.

　　The most accessible blue hole is Captain Bill's Hole, with a swimming deck, toilets and a high platform for leaping into the water. It's easily reached from Andros Town, following a lane that leads inland off the Queens Hwy near Mapen's Store. Rainbow Blue Hole, to the east of the Queens Hwy, is also very accessible. Other blue holes take a bit more effort to reach; marine explorer Jacques Cousteau put the sinkhole known as Cousteau's Blue Hole on the map in the 1970s after releasing dye into the water to prove that the blue hole was linked by underground channels to the sea.

　　With a mask and snorkel, you might spot some of the blue holes' unique cavefish, which have evolved to thrive in these unusual conditions. However, the best blue holes for aquatic life are offshore–the dive center at Small Hope Bay Lodge on the fringes of the national park can arrange dives to several blue holes offshore from Andros that are teeming with marine life.

　　Travel on from Andros to Long Island via Nassau, and you can explore Dean's Blue Hole, the second deepest blue hole in the world, which drops 203m, right off the beach. It's an amazing site for scuba and free-diving, opening onto a chamber that is vastly bigger than the bottleneck opening at the surface.

　　

Getting to Blue Holes National Park

Coming from Andros Town, the access road for the park heads west off the Queen's Hwy along Leroy Hanna Dr from the settlement of Love Hill. Scooters and cars can be rented for exploring. Ask locals to point you towards the tracks leading to specific blue holes. To reach Dean's Blue Hole on Long Island, you'll need to fly into Deadman's Cay airport via Nassau.