Ordered from nearest — out to sea to see the real thing
Sorted from closest to furthest, with an honest note on which you can do by scheduled ferry, which need a tour, and which take the whole day.
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The nearest neighbour and the easiest trip of all — the fast boat from Samui reaches Thong Sala pier in just 20–30 minutes. The whole world knows Phangan for the Full Moon Party, the all-night beach party at Haad Rin where tens of thousands dance until sunrise on full-moon nights. But honestly, that's only one corner of the island.
The other half of Phangan is its very quiet north — Bottle Beach, reachable only by longtail boat or a jungle hike; Thong Nai Pan, a calm bay made for doing nothing; and Chaloklum, a fishing village with seafood tables by the water. Rent a scooter or charter a songthaew, loop the island for the day and catch the late-afternoon boat home. If you're coming for the Full Moon Party itself, special late boats run on party nights but they're packed — many people simply stay over on Phangan. For the full picture, read our Koh Phangan guide.
That postcard image of green limestone islands rising out of the sea in a long line? This is it — Ang Thong National Marine Park, 42 islands about 28 km west of Samui. The highlights are the Emerald Lake (Talay Nai), a green saltwater lagoon hidden inside Koh Mae Ko that you climb a staircase to see from above, and the viewpoint on Koh Wua Ta Lap, which looks out over the whole archipelago — earned with a genuinely sweaty climb.
Most tours leave in the morning and return by evening, with sea kayaking along the cliffs, snorkelling and beach time built in. There is no scheduled public ferry — you go with a tour or a private charter, and the park normally closes during the monsoon, roughly Nov–Dec each year. Before choosing between the big boat and the speedboat, read our full Ang Thong guide.
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If the underwater world is the goal, head straight for Koh Tao — a small island north of Phangan known as one of the cheapest places in the world to learn to dive, with clear water, plenty of coral and snorkelling bays all around the island. In some bays, small blacktip reef sharks cruise past often enough to feel like locals.
Right beside it is Koh Nang Yuan, three islets joined by a white sandbar; a few minutes' walk up to the viewpoint earns you the exact view in this photo. A day trip from Samui works two ways — take the Lomprayah boat independently on the morning departure and return in the afternoon, leaving about 4–5 hours on the island, or join a snorkelling tour that hops between the bays with all the gear provided. Honestly, a same-day return feels rushed; if you're serious about learning to dive, stay 2–3 nights instead. Read more in our Koh Tao guide.
Had your fill of islands and craving jungle instead? The Surat Thani mainland holds Khao Sok National Park, a vast rainforest said to be older than the Amazon. The highlight of a day trip is Cheow Lan Lake (Ratchaprapha Dam) — a green reservoir walled in by sheer limestone peaks that many call Thailand's answer to Guilin. You cruise between the karsts by longtail boat, stop for lunch at a floating raft house, and can swim straight off the deck.
From Samui it takes commitment: a ferry to Donsak first (~1.5 hr), then another 1.5–2 hours by road. Day tours from Samui do exist, but it's a very long day (~12–13 hours). Honestly, if you can make the time, one night in a raft house on the lake is worth far more. On the way back, if you have time to spare, Surat Thani town has a night market and southern-Thai food worth a stop before the boat.