Khao Lak Dive Sites: Similans, Koh Bon, Richelieu Rock & More

Featured image: josh.ev9, CC BY-SA 2.0, via Flickr.

Quick answer: where you dive from Khao Lak

Nearly every dive trip leaves Khao Lak by boat. Day-trip speedboats cover the Similan and Surin national parks in 50 to 80 minutes, depending on the site, according to one local operator. Day trips run two dives. Richelieu Rock appears on that operator's schedule three days a week. Liveaboards combine the northern sites in one itinerary and offer 14 dives over four nights. Pick a day trip for a short holiday. Pick a liveaboard if you want Koh Bon, Koh Tachai and Richelieu Rock in a single trip.

Khao Lak dive sites at a glance

Nine islands make up the Similan chain, about an hour by speedboat from the coast. Surin is a separate national park on the same day-trip circuit. Koh Bon, Koh Tachai and Richelieu Rock are the northern sites. Use this table to shortlist, then read the sections below.

Similan Islands diving: beginner bays and deeper sites

Donald Duck Bay is the entry point for new divers. Sandy patches suit training, and open-water courses run here. Further out, big boulders called whale back rocks offer swim-throughs, coral fans and marine life.

Experienced divers head for North Point, on the northern part of the ninth island. Boulder City sits just off the coast. It is deep and has no shelter from current, and large fish pass above its coral fans. Operator trip reports describe drift dives at Three Trees and challenging currents at Christmas Point. Treat all of these as experienced-diver sites. For island logistics, read our guide to reaching the Similans.

Bleaching hurt the shallows around the islands. A 2024 diving guide reported that some areas were closed to protect damaged reef, and that deeper sections fared better. Anita's Reef, on islands 4 and 5, was among the damaged sites. Current closures and reef status are published by Thailand's national park authority. Coral and marine conservation falls under the Department of Marine and Coastal Resources.

Koh Bon, Koh Tachai and Richelieu Rock: the northern sites

Koh Bon lies north of the Similan chain and is not one of its nine islands. This rocky island has a closed bay for less experienced divers. Operator trip reports mention tuna hunting at Koh Bon Pinnacle. Koh Tachai and Richelieu Rock are also offshore northern sites, which is why they usually mean a longer transfer or a liveaboard. Reports describe barracuda at Koh Tachai and whale sharks at Richelieu Rock. Sightings are never guaranteed.

One local operator runs Richelieu Rock three days a week. On its published schedule, 13 November 2026 was Koh Bon and 14 November 2026 was Richelieu Rock. Check which day matches your dates before booking a day trip.

Closer to shore: Boonsung Wreck

Boonsung Wreck is closer to the coast than the park sites, so it avoids the 50 to 80 minute offshore transfer. It suits divers who want a shorter outing. Depth, visibility and access are covered in our wreck dive guide.

Day trip or liveaboard: how to choose

One operator's current list shows the contrast. Its four-night Similan, Koh Bon, Koh Tachai and Richelieu itinerary offers 14 dives from ฿29,190. Its five-night version offers 18 dives from ฿36,487. Prices checked November 2026. Day trips cost less but stop at two dives.

When to go and what you'll see

One operator's 2026–27 liveaboard schedule runs from October to May. Park access dates have varied by year, so check Thailand's park notices before fixing flights. Our diving season guide breaks the months down. A 2024 diving guide described water of about 28°C and calm conditions. Our water temperature guide covers how that shifts through the year. For turtle sightings near Khao Lak, read about turtle encounters.

Which dive sites match your certification level

Agencies set depth limits by certification level, so your instructor has the final word. This table gives a starting point.

Choosing an operator

Find SSI-affiliated centers through the SSI dive center locator. Compare dives, sites and transfer time across local dive shops. Sea Dragon Dive Center has its own page with the details.

Practical logistics

Expect an early start, a transfer to the boat and a 50 to 80 minute speedboat ride on park day trips. One operator serves lunch after the first dive. Ask whether the national park fee is in the quoted price, since operators handle it differently. Current fees are listed on the park authority's site. Bring motion sickness tablets if boats affect you. Non-divers can snorkel during surface intervals, and our snorkeling trips guide covers options. Phuket has an international airport and is the usual gateway for Khao Lak.

Mistakes to avoid

Most disappointments come from a mismatch between site, season and certification.

• Booking a northern-site day trip in rough sea months.
• Skipping the question of whether the park fee is included.
• Expecting guaranteed big animals at Richelieu Rock.
• Assuming the Similans are beginner-only, when Boulder City and Christmas Point test experienced divers.
• Choosing on price alone instead of comparing dives, sites and transfer time.