Mu Ko Similan, Mu Ko Surin and Mu Ko Lanta national parks will close on Monday in an annual tradition to let nature rehabilitate itself during the monsoon season.
An announcement on the Facebook account dedicated to the three marine parks said visitors will not be admitted from Monday until Oct 14.
The temporary closure follows the policy of the National Parks, Wildlife and Plant Conservation Department to give all the flora and fauna in all parks time to regenerate during the off-peak season for tourists.
Similan and Surin are popular destinations in Phangnga, while Lata in Krabi is also famous for its clear water and white sand.
Thailand officially entered the rainy season last Friday, according to the Meteorological Department.