Andros is the largest island in the Bahamas and is a favourite for scuba divers and fishermen. The island is largely undeveloped, so the atmosphere is very casual and hotels tend to be small and unpretentious. Much of the island is covered with palm savannas, primeval forest and huge mangrove wetlands, making it a bird-watchers paradise. However, it is the underwater life that really makes Andros unique; it has the world's third largest reef running along its east coast for 167 miles (269km). Andros' most famous attractions are the Blue Holes, a network of water-filled caves, both inland and in the ocean, that draw scuba divers from all over the world. The colourful and unique marine life that lies below the tranquil surface makes Andros a fantastic spot for divers, snorkellers, and fishermen alike. Two of the world's first dive-dedicated resorts are located on the island, both running regular scientific research dives as well as purely recreational dives. There are also many different orchids on the island in the mangrove swamps, including several that can be found only on the island, making it a popular destination for orchid hunters. There are several festivals hosted on the island every year, including an annual regatta, a conch festival, a pirate's festival and an annual seafood festival.