The Similan Islands National Park will now be able to limit the number of visitors to limit environmental damage.
The decision from the Supreme Administrative Court this week overturned an earlier ruling from the Phuket Administrative Court.
The Similan Islands are a popular diving spot in the Andaman Sea off the coast of Khao Lak.
The ruling reverses an order of a provincial court last year which said a plan to limit numbers by the Department of National Parks, Wildlife and Plant Conservation was illegal.
Last October the department announced plans to put a ceiling of 3,325 tourists and 525 divers per day into the national park and that visitors could not stay overnight.
Tour operators petitioned the Phuket Provincial Court to annul the limitations as it would severely affect their businesses. In December the Phuket Provincial Court issued an injunction against the visitor limitations but the department appealed against the ruling.
Now the Supreme Administrative Court has declared that tour operators were unable to present valid arguments against the department’s attempts to curb visitor numbers and their efforts to protect the archipelago against further degradation.
The higher court was critical of the Phuket Administrative Court’s ruling, saying that it would have led to “severe damage”.
Limiting tourist numbers at many of the Andaman’s tourist hot spots has become a part of the Department of National Parks, Wildlife and Plant Conservation legal weaponry since closing down Maya Bay, but it is facing pressure from tour operators.