Diving & Snorkelling
The park's dive sites include Ko Surin Tai, Ko Torinla (south) and HQ Channel between the two main islands. Richelieu Rock, a seamount 14km southeast, is also technically in the park and happens to be one of the Andaman's premier dive sites (if not the best). Manta rays pay visits and whale sharks are sometimes spotted here during March and April.
There’s no dive facility inside the park, so dive trips (four-day liveaboards from 20,000B) must be booked through centres in Khao Lak, Phuket and Ranong. Transfers are usually included. There's a 200B park diving fee per day, plus the national park fee (adult/child 500/300B), which is valid for five days.
Though recent bleaching of hard corals means snorkelling isn’t quite as fantastic as it once was, you’ll still see plenty of colourful fish and soft corals. The most vibrant soft corals we saw were at Ao Mai Yai, off Ko Surin Neua. There's good snorkelling at Ao Tao and Ao Pak Kaad, where you might spot turtles, off east and south Ko Surin Tai, respectively. More fish swim off tiny Ko Pajumba, but the coral isn’t great. Ao Suthep, off northern Ko Surin Tai, has hundreds of colourful fish.
The nearest decompression chamber is in Phuket. In the case of an accident, dive operators will contact the chamber's Khao Lak–based SSS Ambulance, which meets boats and rushes injured divers south to Phuket International Hospital.
Half-day snorkelling trips (150B per person, snorkel hire 160B) leave the island headquarters at 9am and 2pm. You'll be mostly in the company of Thais, who generally splash around semi-clothed in life jackets. For more serene snorkelling, charter a long-tail from the national park (3000B per day) or, better yet, directly from the Moken in Ban Moken.
Tour operators in Khuraburi and Khao Lak organise snorkelling day trips to the park (adult/child 3700/2500B).
Wildlife & Hiking
Around park headquarters, you can explore the forest fringes and spot crab-eating macaques and some of the 57 resident bird species, including the beautiful Nicobar pigeon, endemic to the Andaman islands, and the elusive beach thick-knee. Along the coast you’re likely to see Brahminy kites and reef herons. Twelve species of bat live here, most noticeably the tree-dwelling fruit bat (flying fox).