The deep‑blue sanctuary where manta rays glide and world‑class diving begins.

Koh 10 — known as Koh Bon and pronounced locally as koh bon (โคะ บน, soft “bon,” like “born” without the “r”) — is also called Koh Sìp (เกาะสิบ, koh sìp, sìp = 10 in Thai). It is the northernmost island of the Similan archipelago, famous for its deep water, dramatic cliffs, and one of the best manta‑ray dive sites in Thailand. There is no beach, no landing, and no walking on the island — everything happens from the boat, surrounded by open‑ocean blue.

“Koh 10 is where the sea grows deeper and the magic grows bigger.”

The first impression of Koh 10

Koh Bon rises sharply from the water — tall cliffs, rugged rock faces, and deep blue water swirling around its edges. It feels different from the southern sanctuary islands (Koh 1–3). This one is bold, wild, and shaped by open‑sea currents. Boats slow down here because everyone is watching the water, waiting for something extraordinary to appear.

Pam always smiles and says, “This is where the big ones show up.”

The mood of Koh 10

Koh 10 feels powerful and full of possibility. It’s the island that makes divers lean forward in anticipation.

Expect:

• deep, glowing blue water
• dramatic cliffs and rock formations
• strong currents
• open‑ocean energy

“Koh 10 is the Similan island that feels closest to the wild sea.”

Diving at Koh 10 — the highlight of the island

Koh Bon is one of the top dive sites in Thailand, especially for manta rays. The island is home to a manta ray cleaning station, where these gentle giants glide slowly above the reef while small fish clean their wings. During the season, manta sightings are common and unforgettable.

What divers love about Koh 10

• manta rays circling the cleaning station
• dramatic wall dives
• deep coral slopes
• excellent visibility
• nutrient‑rich currents attracting large marine life
• schools of trevally, barracuda, and tuna
• reef sharks in the distance

“Seeing a manta at Koh 10 feels like time stops for a moment.”

Above the water — cliffs, colors, and open sea

Even without landing, Koh 10 is stunning from the boat. The cliffs rise sharply, the water shifts between deep blue and turquoise, and the island feels like a gateway to the open Andaman Sea.

You might see:

• birds circling the cliffs
• waves breaking against the rock
• the horizon stretching endlessly north

Protected nature — no landing, no beach access

Koh 10 is a protected island, just like the southern sanctuary islands. To preserve the manta cleaning station and the reef, there is:

• no beach access
• no landing
• no hiking
• no walking on the island

All activities happen from the boat — diving and admiring the cliffs. This protection keeps the marine ecosystem healthy and thriving.

Why people love Koh 10

• manta rays
• world‑class diving
• dramatic cliffs
• deep blue water
• open‑ocean adventure
• a completely different mood from the southern islands

Koh 10 is the wild, powerful chapter of the Similan story — the island where the sea feels big, the cliffs feel ancient, and the underwater world feels alive