Gotjawal forest refers to the forest covering the rocky area of "AA Lava" on Jeju Island of South Korea. In this article it is shown that Gotjawal forest is an internationally important wetland under the Ramsar Convention. Gotjawal forest should be regarded as a wetland because it is a subterranean hydrological system, which is classified as wetland under the Ramsar Convention. And Gotjawal forest is an internationally important wetland because it is the representative wetland type of Jeju region with hydrological importance, and because it supports rare species of plants.