Koh Samui Diving: Day Boats to Sail Rock and Koh Tao, and the Rules on the Water Since 2025

Koh Samui diving means a day boat to Sail Rock, Koh Tao or Chumphon Pinnacle

The three Koh Samui centers that SSI lists in its register all sell the same shape of day: hotel pickup in the morning, a crossing, two dives with lunch between them, and back on Samui by mid-afternoon. The destinations on their trip pages are Sail Rock, Koh Tao and Chumphon Pinnacle, and one of the three adds Ang Thong. Their timetables agree closely, so the times below are ranges from three operators rather than one number.

Member Diving picks up at about 7:00 to 7:30 and lands divers back on Samui between 2:00 and 3:00 pm from Sail Rock and between 3:00 and 4:00 pm from Koh Tao. The Life Aquatic lists its speedboat at 9:00 to 10:00 to Sail Rock and 9:00 to 10:30 to Koh Tao. Sons of the Sea leaves at 9:00 and gives 50 to 90 minutes to Sail Rock and about an hour and a half to Koh Tao.

The two main runs alternate through the week rather than going every day. Member Diving goes to Sail Rock on Tuesday, Thursday, Saturday and Sunday and to Koh Tao on Monday, Wednesday and Friday. Sons of the Sea sails to Sail Rock on Tuesday, Wednesday, Friday and Sunday, and to Koh Tao and Chumphon Pinnacle on Monday, Thursday and Saturday.

Sons of the Sea's prices start at 4,650 baht for Sail Rock and 4,950 for Koh Tao. Member Diving showed 4,500 and 4,700 on 24 September 2026, marked down from 5,940 and 6,180.

Every training dive from Samui carries a crossing, which is the practical reason people who want to certify often look at Koh Tao itself. The Koh Tao open water course guide has that island's published course prices, and the Koh Tao and Koh Phangan comparison covers the neighbor that shares Sail Rock with it.

The northeast monsoon held the Gulf around Koh Samui for almost all of November 2025

The Thai Meteorological Department publishes a summary for every month, and the most recent northeast monsoon is a concrete guide to what the season looks like here. For November 2025 it recorded that the monsoon “prevailed over the Gulf of Thailand, the southern region and the Andaman Sea almost the whole month and became rather strong at the end of the month”. A low-pressure cell covered the lower Gulf from 19 to 21 November.

The east coast of the south, the side Samui sits on, took 311.3 mm of rain that month. December 2025 was different: the department describes a moderate to rather active monsoon over the Gulf almost all month and rain mainly along the east coast, but only 97.9 mm of it, in a month the department put at about 41 percent below normal rainfall across Thailand. One year is one year, and the department's monthly pages are the place to watch before booking boat days late in the year.

The park authority works to the same calendar. Mu Ko Ang Thong, the national park west of Samui, closed named beaches, a lagoon, bungalows and a campsite from 1 November to 15 December in 2024, covered in the Ang Thong section below. For anyone staying the year on a Destination Thailand Visa, November is the month to plan desk work rather than boat days.

Koh Samui's 2018 reef order gave itself a two-year life

The rule English summaries still quote for Samui's reefs is Department of Marine and Coastal Resources Order 755/2561, signed on 17 August 2018 and published in the Royal Gazette, volume 135, special issue 211 D, on 31 August 2018. It was made under section 17 of the Act on the Promotion of Marine and Coastal Resources Management of 2015 and covered Koh Tao, Koh Phangan and Koh Samui together.

Its four bans were narrower than the summaries suggest. Clause 1 barred anchoring on coral reef in a manner that causes danger or damage to it, and required boats to tie to a mooring buoy where there is one. Clause 2 barred feeding aquatic animals for the purpose of luring, catching or collecting them. Clause 3 barred dumping waste or wastewater into the sea, and clause 4 barred sea-walker tours and anything else that affects the reef.

Clause 7 is the one that matters now. The order took effect ninety days after publication, which the department put at 1 December 2018, “for a period of two years”. Summaries written while it ran, such as the Thaiger's of January 2019 with its prison term of up to one year or fine of up to 100,000 baht, are still online and carry no end date. The department's own index of its section 17 orders, read on 24 September 2026, lists no successor for the three islands.

What the 2025 notification bans in the sea around Koh Samui

What does bind the water now comes from a different law. A Ministry of Natural Resources and Environment notification signed on 24 April 2025, under section 45 of the Enhancement and Conservation of National Environmental Quality Act of 1992, was published in the Royal Gazette on 21 May 2025. Clause 18 puts it in force from the following day for five years. It replaced a 2014 notification for the same subdistricts of Samui and Phangan.

It divides the area into seven zones. Area 1 is the sea inside a box drawn in UTM coordinates, X 595,000 to 637,300 and Y 1,027,000 to 1,087,716, excluding petroleum block G5/43. Converted to latitude and longitude, that runs from about 9.29 to 9.84 degrees north and 99.87 to 100.25 degrees east: the water around Koh Samui and Koh Phangan. Area 7(2) is a second sea box around Koh Tao.

Clause 5(1) then lists what is prohibited in both sea areas, and four items concern a diver. The anchoring item bans anchoring, or any act that affects the seabed, where there are seagrass beds, coral reefs, artificial reefs, coral rock and natural underwater rock piles. Unlike the 2018 order, it says nothing about the anchor having to cause damage. Its examples are sea-walker tours, glass-bottom boats and boats that use air pressure to push water out for fish viewing.

The marine life item bans collecting, destroying or harming sea turtles, ornamental fish, giant clams, sea fans, starfish, sea anemones, coral, dead coral, coral rock and seagrass, except permitted research and public utilities. Dead coral on that list means a broken fragment picked up as a souvenir is covered. Two more ban fishing in coral reef areas and discharging waste into the sea unless it has been treated to the legal standard.

One item reaches past diving: it bans water scooters, jet skis, hydrofoil boats, banana boats and similar craft except in zones the province designates for them. The navy is exempt from the scooter and the anchoring items when it uses the area for official purposes.

Sail Rock from Koh Samui falls in the Koh Tao area of the 2025 rules

Sail Rock has its own entry in Thai law. The marine department's Order 1148/2563, signed on 26 August 2020 and published on 23 September 2020, banned fishing, traps and nets of every kind on the coral at eight named pinnacles and islets in Koh Phangan district, and Kong Hin Bai, the Thai name for Sail Rock, is one of them. Its map 5 of 11 draws Hin Bai as a box about 600 meters on a side, from 9°56'31" to 9°56'51" north and 99°53'51" to 99°54'11" east.

That order carried a penalty of up to one year in prison or a fine of up to 100,000 baht under section 27 of the 2015 Act, and it too had an end date: clause 5 gave it three years from publication, which ran out in September 2023. The same order listed Chumphon Pinnacle, the other pinnacle on the Samui boats' schedule.

Converted into the coordinates the 2025 notification uses, the Hin Bai box sits at about X 598,400 to 599,000 and Y 1,099,150 to 1,099,750. That is inside Area 7(2), the Koh Tao box, which runs from Y 1,095,500 northwards, and outside Area 1. Chumphon Pinnacle falls in Area 7(2) as well. The bans are the same list in both areas, so the practical point is the anchoring clause, whose “natural underwater rock piles” describes exactly what Sail Rock is.

Between the northern edge of Area 1, near 9.84 degrees north, and the southern edge of Area 7(2), near 9.91, is a strip of open water about 8 km wide that neither sea area covers. The Samui boats cross it on the way out. The photograph at the top of this page, taken in 2006, shows boats tied up at the rock years before either rule was written.

Ang Thong, the national park west of Koh Samui, charges foreign adults 200 baht

Ang Thong is a national park, and a park brings its own fee, calendar and rules. The fees come from a Department of National Parks regulation of 2021, gazetted on 9 December 2021 and in force from 7 June 2022, which sorts every park into four groups. The department's own list puts Mu Ko Ang Thong in group 2: 40 baht for a Thai adult and 20 for a child, 200 baht for a foreign adult and 100 for a child.

The 300 baht figure on commercial Ang Thong pages is the rate the same schedule sets for group 3, and Ang Thong is not in group 3. Sons of the Sea states that its Ang Thong dive day includes the park fee. If your operator's does not, ask at the ranger station, because the department announced this schedule in June 2022 and can change it.

The seasonal closure is narrower than “the park is closed”. The 2024 notice, relayed by the government's Anti-Fake News Center, closed Ao Kha beach, Koh Wua Ta Lap, Hat Sam Sao, the Thale Nai lagoon, Hat Na Thap, Hat Tham Rang, Hat Song Phi Nong, bungalow zone 1 and the Wua Ta Lap campsite from 1 November to 15 December. It names beaches, a lagoon and places to sleep; check each year's notice rather than assuming the dates carry over.

The sunscreen rule applies inside the park. A Department of National Parks notice published in the Royal Gazette on 3 August 2021 bans bringing into, or using in, a national park any sunscreen containing oxybenzone, octinoxate, 4-methylbenzylidene camphor or butylparaben, on pain of a fine of up to 100,000 baht. It covers national parks as such, not only marine ones. The reef-safe sunscreen guide sets it beside the other bans divers meet.

In 2024 the marine department logged Koh Samui's reefs as pale and Koh Tao's bays at 51 to 90 percent bleached

The heat of 2024 reached this part of the Gulf hard. The marine department's bleaching bulletin for April and May 2024 says daily sea temperatures that year ran above those of earlier bleaching years, including 2010, with bleaching reported from mid-April to the end of May. It puts May at 86.6 percent nationally, 92.3 percent for the Gulf side and 76.7 for the Andaman side, without saying in that sentence whether it is counting sites or coral.

Its site table is more specific. All five Koh Samui monitoring points, at Laem Chon Khram, Laem Nan, Laem Lamai, Laem So and Taling Ngam, sit in the category pale coral, which the bulletin keeps separate from its bleaching classes. Koh Tao's Ao Tanot, Chalok Ban Kao and mid-bay points sit in the 51 to 90 percent class, while other Koh Tao points ranged from pale to 11 to 50 percent. Hin Bai does not appear among the sites listed.

The same bulletin lists what the parks did about it. At Ang Thong, kayaking and other recreation were suspended at Ao Kha, Koh Wua Ta Lap, Koh Mae Ko and Koh Sam Sao. The bulletin describes April and May 2024, not the reef you will see; the department's bleaching site publishes later issues, and a dive center that went out last week knows more than either.

Bangkok Hospital Samui's list of its clinics names no hyperbaric unit

A diving blog from 2015 describes a single-person hyperbaric chamber at Bangkok Hospital Samui in Chaweng. The hospital's own directory of its centers and clinics, read on 24 September 2026, lists trauma and emergency, intensive care, a referral center, wound care and about two dozen other departments, and no hyperbaric or oxygen therapy unit. The group's Phuket branch, Bangkok Hospital Siriroj, does publish a hyperbaric chamber page on the same site.

So this page names no chamber on Samui. The Koh Tao and Koh Phangan comparison recorded a recompression chamber on Koh Tao as its operator published it on 5 September 2026; that operator's site refused automated reading on 24 September, so no phone number is repeated here. Ask your dive center which chamber its emergency plan names, how an injured diver gets there, and who pays, then check the answer against your policy in the dive insurance guide.

Three Koh Samui dive centers sit in the SSI register, and that list is short

The Koh Samui operator list holds 3 dive centers, read on 24 September 2026, all published by SSI in its register of affiliated centers. SSI files Member Diving under Bophut and the other two, Sons of the Sea and The Life Aquatic, under Koh Samui and Surat Thani. All three publish a website in the register.

Three is not the number of dive shops on Samui, and the reason is where the list comes from. SSI publishes its whole register, 3,868 centers worldwide on the date read, so its Samui entries can be listed and each one opened. PADI's shop locator applies the country in the browser rather than on the server, so it cannot be read as a list. Thailand's tourism business licenses are not published as a list this directory can read.

So a Samui shop that teaches PADI, or is simply not in SSI, is missing from the list without anything being wrong with it, and absence means nothing. What an entry proves is also narrow: SSI registers the business on the date given, and nothing about the boat, the teaching or whether it is open this season. Which registers can be read explains each source's limits, and the Koh Tao and Koh Phangan lists cover the islands the Samui boats visit.