Snorkelling on Koh Samui: The Best Spots

Koh Samui sits in the middle of the Gulf of Thailand, and there are some genuinely good spots around the island to put on a mask and snorkel — some right off the beach, others only reachable by boat. Here's where to go, an honest answer on sharks, and a few rules that protect both the reef and you.

Snorkelling straight from the beach

Not every beach on Koh Samui works for snorkelling — most of the island's long sandy stretches, like Chaweng or Lamai, have a sandy bottom with little to see. A handful of smaller, rockier bays do have a genuine house reef you can reach without a boat:

• Silver Beach (Thong Ta Khian), between Chaweng Noi and Lamai: considered the island's best house reef. Rocks on both sides of the small bay shelter parrotfish, butterflyfish and, occasionally, blue-spotted rays.
• Coral Cove, south of Chaweng: a small bay between granite boulders with channels and overhangs. Visibility is best in the morning, before the afternoon wind picks up.
• Choeng Mon, around the headlands of the bay: shallower, calmer coral patches — good for families and beginners, if less dramatic than the other two.

At all three, the experience depends heavily on the weather. Early morning or late afternoon usually gives you calmer, clearer water.

Snorkelling by boat: the islands around Koh Samui

If you want more than a house reef, a boat trip is hard to avoid. Three destinations stand out:

Koh Tan and Koh Madsum (Pig Island)

Just 15 to 20 minutes from Thong Krut in the south of Koh Samui lie Koh Tan, with a quiet coral reef and few residents, and the well-known Pig Island, Koh Madsum. Good for a shorter trip that combines snorkelling with a beach day. Full details in our article Pig Island: Koh Madsum, the Island of Pigs.

Koh Tao and Koh Nang Yuan

Around 90 minutes away by speedboat lies one of the best-known diving and snorkelling areas in the Gulf of Thailand. The reefs are shallow enough in places that you'll see plenty with just a mask and snorkel: parrotfish, anemones with clownfish, and with a bit of luck a turtle. One thing to note: fins aren't allowed while snorkelling at Koh Nang Yuan, to protect the shallow coral. More in our article Koh Nang Yuan & Koh Tao: The Day Trip.

Ang Thong National Park

Honestly, Ang Thong isn't a top snorkelling destination — the water is often murky with sediment, and the reefs are nowhere near as impressive as those at Koh Tao. The scenery still makes it worth a visit in its own right. Important for 2026: the national park is officially closed from 1 November to 15 December, with no tours running during that period. More in our article Ang Thong National Park: The Day Trip.

Matching tours

Two boat tours on kohsamui.tours that head out specifically to snorkel:

Sunset snorkelling at Koh Mudsum and Koh Tan — shorter, in the late afternoon:

from 1,550 THBSunset snorkeling tour pig island Koh Mudsum & Koh Tan★★★★★4.73 from 22 reviews

Koh Tao & Koh Nang Yuan day trip — for anyone who wants to see the most intact reefs in the region:

from 1,850 THBDay trip snorkeling Koh Tao & Koh Nang Yuan★★★★★4.78 from 170 reviews

Are there sharks in Koh Samui?

Yes — but the honest answer is that it's nothing to worry about. Blacktip and whitetip reef sharks live on reefs in the region, typically shy and small. They're seen a little more often near Koh Tao and Koh Nang Yuan than right off Koh Samui itself. No attack has ever been recorded from either species. Across the whole of Thailand's recorded history, only four unprovoked shark attacks are confirmed, with no fatal incident in over 50 years. The actual risks while snorkelling are far more mundane: sunburn, cuts from coral or rocks, the occasional jellyfish, and seasickness on the crossing.

Reef protection and safety

• Mineral sunscreen (zinc oxide instead of oxybenzone/octinoxate) is kinder to the reef.
• Never touch or stand on coral — not even for a quick rest.
• Keep your fins still to avoid stirring up sand or sediment — fins are banned outright at Koh Nang Yuan.
• Choose operators with visible environmental standards, such as Green Fins guidelines.
• Never snorkel alone, watch for currents, and ask your guide if you're unsure about conditions.

Best time to snorkel

The water is usually calmest and clearest between March and September, when the sea is settled. In the rainy season, usually October to December on Koh Samui, visibility often drops and boat trips are occasionally cancelled. More on the weather through the year in Koh Samui weather and the truth about the rainy season.

Frequently asked questions

Are there sharks in Koh Samui?

Yes, small reef sharks such as blacktips and whitetips occur in the region, more often near Koh Tao and Koh Nang Yuan. They're shy, incidents with snorkellers are extremely rare, and they aren't the thing to be cautious about — sunburn and coral cuts are the real risks.

Where is the best snorkelling area?

The reefs around Koh Tao and Koh Nang Yuan are considered the most intact in the region, and easily reached on a day tour from Koh Samui. Right from the beach, Silver Beach is the best house reef.

Where can you snorkel a house reef?

At Silver Beach (Thong Ta Khian) between Chaweng Noi and Lamai, the reef reaches almost to the shoreline. Coral Cove, south of Chaweng, also has a small reef accessible straight from the beach.

Which beach is the most beautiful?

That's a matter of taste, but Coral Cove and Silver Beach are among the island's most photogenic small bays — not for the length of sand, but for the rocks, the calm and the clear water.

For more on the islands off Koh Samui, see our articles on Pig Island: Koh Madsum, Koh Nang Yuan & Koh Tao and Ang Thong National Park, as well as our Top 10 beaches on Koh Samui.