The Similan Islands (, , , Malay: Pulau Sembilan) is an archipelago in the Andaman Sea off the coast of, and part of, Phang Nga Province in southern Thailand. It is the maritime border between India and Thailand. It was established as Mu Ko Similan National Park in 1982 after a one-year assessment by the forestry department. Access and tourism Access to the Similan Islands is easiest from Tab Lamu Port, just south of Khao Lak in Phang Nga Province. The park headquarters is in Tab Lamu, which is a small fishing village, just 13 km from Bang La On in Khao Lak. Boats depart daily from the middle of October to the middle of May. The trip takes about three hours each way on slower boats or 70 minutes via speedboat. During the diving season liveaboard boats head to the Similan Islands. These dive boats depart and return from Tab Lamu, Ko Lanta, Phuket, and Ranong and stay for several days at Similan National Marine Park. The Similan Islands Park is the most overcrowded Thai national park. Five to six thousand persons per day visit the islands during its open season from mid–October to mid–May. The DNP reports that since October 2017 the park has been visited by 883,438 persons. Sheer numbers have resulted in degradation and thus increased regulation. The park is closed in the rainy season, from 16 May-15 October, every year. The island of Ko Tachai has been closed to tourists indefinitely beginning 15 October 2016 to allow it to recover from effects of its heavy tourist burden. As of the park's re-opening on 15 October 2018, the number of visitors allowed to visit the islands was capped at 3,850 per day in order to slow environmental destruction. Prior to the visitor cap, the islands received about 7,000 visitors per day. In 2017, about 912,000 tourists visited. Tour operators have protested the new rules, saying jobs will be lost. All overnight accommodations on the islands have been demolished as part of the rehabilitation program. Geography The islands are at The park is an archipelago consisting of 11 islands, occupying an area of 87,500 rai ~ with a land area of about . For convenience, the Thai Department of National Parks (DNP) has assigned numbers to the islands. From north to south, they are: Island 11: Ko Tachai Island 10: Ko Bon, also known as Ko Talu