🔄 Updated 21 Jun 2026
First, the honest heads-up: this trip has a hard season. Mu Ko Similan and Mu Ko Surin National Parks open from roughly 15 October to 15 May each year. Outside that window they close so the reefs can recover, and no boats go out. If you're planning a diving trip, always check the dates before you book flights.
We use Khao Lak as the main base because it's close to Thap Lamu Pier (for the Similans) and has transfers up to Kuraburi Pier for Surin. Khao Lak itself has dive shops that have been running for decades, so you can pick either a day trip (out in the morning, back by evening) or a liveaboard (sleeping on the boat). The plan below is the 4-day version that gets you the most time in the water without overnighting on a boat.
Who this trip is for
- Certified divers (Open Water and up) — the Similans and Surin have sites for every level, but some spots have strong currents, so they suit people who've done a bit of open-water diving before.
- First-timers wanting to try (Discover Scuba) — Khao Lak shops run try-dives with an instructor in shallow water, no certification needed.
- Snorkellers — if you're not going deep, Surin has shallow water and gorgeous coral; it's actually better for snorkelling than the Similans.
Arrive in Khao Lak, settle in, check in with your dive shop
Day trip diving the Similan Islands
A Similan day trip runs roughly 3,000–3,400 THB per person for snorkelling or a try-dive; a 2-dive scuba package costs more than that, depending on the shop. The price usually includes transfers, food, and gear, but check whether the national park fee is already included (around 400 THB per adult; foreigners pay more).
Day trip to the Surin Islands + Richelieu
A Surin day trip is roughly 3,200 THB plus another 500 THB or so for the park fee per adult (kids are cheaper). For serious diving at Richelieu Rock, you'll usually need a dedicated scuba trip or a liveaboard, since it's far out — two dives plus a fairly long boat ride.
Book the activities in your Phang Nga trip ahead
Booking online ahead on Klook or GetYourGuide is usually cheaper than the gate and skips the queue. Pick only the experiences you actually want — prices and availability are shown live on each site.
Dive sites worth knowing
Richelieu Rock
A horseshoe-shaped pinnacle out in open water near the Surin Islands, known for the sheer variety of marine life and the chance of whale sharks late in the season. Plenty of people rate it among Thailand's top dive sites.
Koh Bon
An underwater rock wall that's one of the most reliable manta-ray spots in the Andaman. It sits between the Similans and Surin and is usually part of a liveaboard route.
Koh Tachai
A pinnacle and reef thick with fish, with strong currents at times. Best for divers who've handled some current before.
Similan Islands, Islands 8–9
Giant underwater boulders with caves and swim-throughs, and visibility that lets you see a long way. The classic stop on a day trip from Khao Lak.
Surin Islands, shallow bays
Dense shallow coral and bright little fish — better for snorkelling and beginners than as a deep dive.
About timing
If you're hoping to see whale sharks and manta rays, the months people mention most are February through April — clearer water and big animals coming through more often. But nothing's guaranteed; the sea is the sea. Some days you'll see them everywhere, some days nothing at all.
Take it easy before heading home
What to prep and what to budget
- Dive certification + logbook — most shops want to see your card and dive history. If you haven't dived in a while, you may need a refresher first.
- Motion-sickness pills — the boats head into open sea and the swell picks up at times. Take them 30 minutes before you board.
- Reef-safe sunscreen — the parks are strict about coral, so pick a type that won't harm the reef.
- Total budget per person, 4 days — two days of diving/snorkelling runs about 6,000–8,000 THB, plus hotel, food, and transport; figure roughly 12,000–18,000 THB depending on your style.
- Liveaboard as an option — if you want more time in the water and a proper crack at Richelieu, there are 3–4 day overnight-boat packages from Khao Lak with 3–4 dives a day.
A safety word
Don't book your last dive on the same day you fly — leave time for your body to off-gas nitrogen. And pick a shop with proper certification (PADI/SSI, for example), insurance, and gear in good condition. A price that's unusually cheap usually comes at the cost of safety.
Want a place to stay near the Khao Lak piers? Here are the well-reviewed options.
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