Koh Bon: Manta Dive Site North of the Similan Islands

Featured image: oliver.dodd, CC BY 2.0, via Flickr.

Koh Bon at a Glance

Koh Bon sits off Phang Nga province, about 50 km west of Khao Lak. It is an uplifted limestone island, roughly 20 km north of the Similan Islands. Dive operators also call it Bon Island, and one west-side site is listed as The Bay. Most trips treat it as a northern add-on to a Similan dive site guide itinerary.

A different Koh Bon exists near Rawai in south Phuket. That island is a long-tail boat beach day, with no diving logistics. Nothing below applies to it. If a Rawai beach afternoon is your goal, look for a Phuket boat guide instead.

• Location: Andaman Sea, about 50 km west of Khao Lak
• Position: about 20 km north of the Similan Islands
• Terrain: uplifted limestone island with a long, narrow ridge on the west side
• Known for: manta rays, a hard-coral wall, and a bay site

Why Divers and Snorkelers Visit

Manta rays are the headline. Operators describe them feeding in the current and visiting a cleaning station on the reef. Sightings are not guaranteed, and a trip can pass without one.

On the west side, a long narrow ridge drops along a wall of hard coral. Divers report nudibranchs, octopus and moray eels along it. Whale sharks are mentioned near the bay, but treat them as a bonus rather than a plan.

Snorkelers also visit, mostly on boat programs that stop here. Ask whether snorkelers get their own briefing and a boat-side guide, because currents can pull swimmers off the ridge.

Getting There: Liveaboard, Day Trip, or Land Base

Koh Bon is 50 km offshore, so the crossing is a real commitment. Most visitors arrive on a North Andaman liveaboard. Some day-boat programs from Khao Lak may include it, depending on sea state and the day's rotation.

One published six-day liveaboard route that includes Koh Bon lists 15 dives. Guests meet a van in Phuket, and the boat departs at 21:00 on day one. The same listing says dive sites are subject to change with weather, waves and wind.

Khao Lak is the closest mainland base. Phuket works for liveaboard departures and longer transfers. Pick the base that matches your operator's pier, not the one with the nicest beach.

Best Time to Go and Park Season

Marine park access follows the season set by Thai authorities. For opening dates, fees and closures, start with the Department of National Parks. One published Koh Bon liveaboard departs on 10 February 2027, so mid-season trips are plainly on the calendar.

Park staff can close individual sites to let coral recover. East of Eden in the Similans is a listed example. A site open last year may not be open on your dates.

Costs and What's Included

Rates change by date and cabin, so no single price fits every trip. Compare options by structure rather than by headline fare. A liveaboard bundles bunk, meals and dives. A day trip costs less outright but covers fewer dives.

Sample listings show common extras. These are worth asking about before you pay.

• Park entrance fee, often paid separately
• Equipment rental, charged per day
• Dive computer rental, charged per day
• Torch rental for night dives
• Airfare and transfers beyond the pier shuttle
• Tips for the boat crew

Who Koh Bon Suits

Koh Bon suits certified divers who are comfortable in current. Water here is reported as clear and warm. Even so, a colder current can arrive and run fairly strong.

New divers should ask about the exact site and depth before booking. Gentler reefs on the Similan side may suit a first open-water trip better.

Snorkelers can enjoy the surface on calm days with a guide. Skip it if you are uneasy in open water or in current.

Koh Bon vs Koh Tachai vs Similan Sites

Few itineraries have room for everything, so choose by goal. Pick Koh Bon for the manta chance and the west-side wall. Compare it with Koh Tachai dive trips, the nearest alternative.

Choose the Similans for variety and easier reef options. Elephant Head Rock dives sit between islands 7 and 8. Reef profiles at Christmas Point dive site make a sensible comparison. Donald Duck Bay stops fit a calmer day.

Island-based pages help you plan what a day trip covers. See Similan Island 4 day trips for one example. Similan Island 8 visits cover another.

Wildlife You May See

Treat this list as possibilities, not promises. Sightings vary by day, current and season.

• Manta rays, the main reason to visit
• Moray eels, the most commonly logged species at the site
• Barracuda and jackfish in open water
• Octopus along the wall
• Banded sea kraits
• Whitetip and blacktip reef sharks, reported less often
• Nudibranchs for macro-minded divers

Mistakes to Avoid and What to Ask the Operator

Most problems come from assumptions made before booking. Avoid the common ones, then ask direct questions before you pay.

• Confusing this island with the Rawai beach island
• Assuming a manta sighting is guaranteed
• Booking without checking park closure dates
• Underestimating the current
• Ask whether Koh Bon is on your itinerary or only possible
• Ask about site rotation and group size
• Ask for a current briefing from the guide
• Ask what the park fee covers and what it does not