Description & Facts: Tourism accounts for 70-75% of the annual GDP of the Cayman Islands. Of the millions of tourists that visit the islands annually, 99% visit Grand Cayman. George Town also serves as a major cruise ship port, which brings in 4,000 to 22,000 tourists a day, five days a week, depending on the number of ships in port. One of Grand Cayman's (GCM) main attractions is the world-famous Seven Mile Beach on which a number of the island's hotels and resorts are located. Seven Mile Beach is regarded by many as one of the best beaches in the world. Historical sites in GCM such as Pedro St. James Castle in BoddenTown also attract visitors. The Sister Islands - Little Cayman and Cayman Brac - also supply their own unique charm. The Cayman Islands is regarded as one of the world's best SCUBA diving destinations because of its crystal-clear waters and pristine walls. Cayman Brac and Little Cayman are also elite SCUBA dive destinations. There are several snorkelling locations where tourists can swim with stingrays including the popular Stingray City, Grand Cayman. Divers find two shipwrecks off the shores of Cayman Brac particularly interesting including the MV Keith Tibbetts. Other Grand Cayman tourist attractions include the Ironshore landscape of Hell, the 23-acre (93,000 m2) marine theme park Boatswain's Beach, also home of the Cayman Turtle Farm, the production of gourmet sea salt, and the Mastic Trail, a hiking trail through the forests in the centre of the island. On Cayman Brac, a lighthouse and a few local museums are tourist draws. Little Cayman's wildlife attracts nature lovers, especially bird watchers in search of the island's Red-footed Booby population. Art and Culture are other features of the Cayman Islands that attract international attention. The National Museum and National Gallery preserve contemporary and dated art works of local and international talent. A Cultural History Exhibition is displayed within the museum, and teaches patrons about historical customs and traditions native to the Cayman Islands. The Gallery sponsors eight exhibitions every year and is located in the Harbour Place in George Town.