The Similan and Surin Islands are the two headline marine parks off the Khao Lak coast, and visitors often have to choose between them. We run trips to both, so here’s an honest, side-by-side comparison to help you pick the one that fits your trip.

The Similan Islands — granite, big blue, and dive sites

The Similans are famous for their dramatic granite boulders, white-sand beaches and deep, clear water. They’re a world-class diving destination and the more popular of the two, so day trips can be busier in peak season. The departure pier is closer to Khao Lak (Thap Lamu), which means a shorter boat ride. If your priority is iconic scenery, postcard beaches and the best big-blue diving, the Similans win.

The Surin Islands — shallow coral and a quieter day

The Surins sit further north and are reached from Kuraburi Pier. The draw here is snorkelling: extensive, healthy shallow-water coral reefs that are arguably the best in Thailand for snorkellers, plus the chance to visit a Moken (“sea gypsy”) village. The Surins are generally quieter and less developed than the Similans, so the day feels calmer. If you mainly snorkel (rather than dive) and prefer fewer crowds, choose the Surins.

Quick comparison

  • Best for diving: Similan
  • Best for snorkelling: Surin
  • Scenery: Similan (granite boulders, beaches)
  • Crowds: Surin is quieter
  • Culture: Surin (Moken village)
  • Departure: Similan from Thap Lamu (closer); Surin from Kuraburi (further north)
  • Season: Both close in the monsoon — roughly mid-May to mid-October

Both parks close during the southwest monsoon, so they’re day-trip destinations from roughly mid-October to mid-May. See our Similan day trip and Surin day trip — and if you have time for both, doing the two on separate days is the best way to experience the full range of the Andaman’s reefs.