Measuring 30km long and 6km wide, the island forms part of the Ko Lanta archipelago, which covers an area of 180 km². The area was designated as Park No.62 of Thailand in 1990.

Less well known than the neighbouring Phi Phi and Phuket islands, Lanta is relatively less developed with most of the accommodation available being basic bamboo huts. There are very few paved roads on the island, mostly to the north and they deteriorate gradually towards the southern end.

Ban Saladan, the main town and port, is located at the northern tip of the island and is served by ferries from Krabi, Phuket and Phi Phi. The main beaches are located on the west of the island, the largest being Klong Dao, Pra-Ae (Long Beach) and Klong Khong Beach. There are other, much less accessible, beaches at the southern end.

Lanta escaped the worst of the 2004 Indian Ocean earthquake. Although there was widespread devastation along the west coast, significantly fewer injuries and fatalities were reported in comparison to the Phi Phi Islands. It is thought 11 people lost their lives. Assisted by tourists, most businesses were up and running within a few days.