Wildlife of Ang Thong Marine Park

The dusky langur is the animal most visitors remember. Soft grey fur, black face and big white rings around the eyes that make it look permanently surprised. Babies are born bright orange and keep that colour for their first weeks, so a troop with young stands out immediately. Langurs eat leaves, live in family groups and are calm around people because nobody feeds or bothers them here.

Look for them on Koh Wua Ta Lap around the park headquarters and along the lower part of the viewpoint trail. Early morning and late afternoon are the active hours; in the midday heat they rest high in the trees. Watch quietly and they often come surprisingly close on their own.

The park's other monkey is a different character. Long-tailed macaques are bolder, louder and clever around anything that smells of food. You will meet them near the beaches and the mangrove edges, often working the tide line for crabs and shellfish, which is where their other name, crab-eating macaque, comes from.

Keep zips closed and food inside your bag, and do not feed them, however confident they act. A macaque that learns bags contain lunch becomes a problem animal, and the rangers are strict about it. Telling the two monkeys apart is easy: langurs sit still and watch, macaques are already walking toward you.

Look up during the crossing and around the anchorages. The white-bellied sea eagle is the biggest bird in the park, white below with grey wings and a wingspan around two metres, usually patrolling the cliff lines or circling over the channels between islands. The brahminy kite is smaller and unmistakable, chestnut red with a clean white head and chest.

Both hunt fish from the surface, and if you are lucky you will see the strike: a long glide, feet down at the last second, then away with the catch. The boat ride is genuinely one of the best birdwatching sessions of the day, so do not put the camera away between islands.

Hornbills live in the taller forest, unmistakable in flight with the heavy casqued bill that makes them look prehistoric. You hear the wingbeats before you see the bird. The species on the park's records is the oriental pied hornbill. The islands also hold collared kingfishers in bright turquoise, glossy hill mynas with their yellow head wattles, and the white-rumped shama, a modest-looking bird with one of the best songs in Thailand.

Bird activity peaks in the first hours after sunrise, so the earlier boats give the best listening. On the viewpoint trail, stop at the quiet switchbacks for a minute; the forest starts moving again the moment a group stops making noise.

Water monitors are the park's dragons, routinely a metre and a half long and completely unbothered by their own reputation. They swim between the rocks, patrol the beach edges and scavenge whatever the tide brings in. Around the headquarters on Koh Wua Ta Lap you have a fair chance of watching one cross the sand in no hurry at all.

They are shy of people and harmless if left alone. Give one a couple of metres of space and it will carry on as if you were furniture.

Put a mask on at the snorkel stops and the species count jumps. Sergeant majors in their prison stripes, parrotfish grinding away at the coral, butterflyfish in pairs, and shoals of fusiliers moving like weather. In the shallow lagoons juvenile blacktip reef sharks pass through, small, cautious and gone before most people are sure what they saw.

Green and hawksbill turtles are recorded in the park and do turn up, but treat a sighting as a bonus rather than a promise. Visibility is best in the calm months from around February to May; after heavy rain the water carries more sediment.