National parks in Thailand (Thai: อุทยานแห่งชาติทางบก) are defined as an area that contains natural resources of ecological importance or unique beauty, or flora and fauna of special importance. Currently there are 102 national parks (including 21 marine national parks, อุทยานแห่งชาติทางทะเล). Often forest parks (วนอุทยานใน) are miscalled as national parks as well.
The parks are administrated by the National Park, Wildlife and Plant Conservation Department (DNP), which is part of the Ministry of Natural Resources and Environment (MONRE). The department was newly created in 2002, and took over the national parks from the Royal Forest Department of the Ministry of Agriculture.
The first national park was Khao Yai in 1961, when the National Park Act B.E. 2504 was passed. The first marine park was Khao Sam Roi Yot, established in 1966. In 1993 the administration of the national parks was split into two divisions, one for the terrestrial and one for the Marine National Park Division (MNPD).
Controversies about Thailand's national parks include excessive development and private concessions. Ko Samet, and other island-based national parks, are particularly impacted by private concessions, often in the form of excessive bungalow developments. Further, many of the northern parks are greatly impacted by illegal swidden farming and poaching.
There are 33 national parks and three marine parks in the process of creation, and are scheduled to be officially gazetted in the future.