Designated as a national park in 1982, the Similan Islands constitute an archipelago of 11 landmasses situated 70 kilometers from the Phang Nga Province coast within the Andaman Sea. This park encompasses a total area of 140 square kilometers, with 26 square kilometers comprised of terrestrial terrain.

Renowned for their abundant marine life, characterized by both hard and soft coral reefs, as well as their pristine waters and white sandy beaches, the Similan Islands are widely regarded as one of the premier diving destinations globally. The islands are distinguished by their distinctive features, including massive rock formations, shallow coastal waters, and lush tropical forests.

Regrettably, the islands have been grappling with issues related to excessive tourism. One of the islands severely affected by this concern, Ko Tachai, has been closed to visitors since 2016 and remained closed as of 2021. In 2018, due to the escalating problem of overcrowding, park authorities imposed restrictions on the daily number of visitors to the Similan Islands, initially capping it at 3,850 individuals and later reducing it to 3,325 visitors per day. Prior to the implementation of these limitations, the islands were accommodating as many as 7,000 visitors on a daily basis.