Phuket vs Koh Tao: Which Thai Dive Base in 2026?
by Yannick SchrothAug 26, 20266 min read
Photo: Eli Duke, Wikimedia Commons, CC BY-SA 2.0.
Best for
- Year-round diving, the cheapest certification and the most independently assessed operators: Koh Tao
- Similan liveaboards and an island with more going on than diving: Phuket, mid-October to mid-May
| Phuket | Koh Tao | |
|---|---|---|
| Signature | Similan day trips and liveaboards | The cheapest certification anywhere |
| Season | Similans shut roughly mid-May to mid-October | Year-round |
| Operators we list | 61 | 58 |
| In the Green Fins register | 8 | 28 |
| Assessed in person | 8 of 8 | 24 of 28 |
| Tier spread | 1 Gold, 4 Silver, 3 Bronze | 4 Gold, 18 Silver, 2 Bronze, 4 Digital |
| Certification cost | We did not verify one | PADI Open Water around $340 |
| Instructor languages | Not published by any of the 61 | Not published by any of the 58 |
| Visa | Thailand's DTV | Thailand's DTV |
| Best for | Liveaboards, in season, and a bigger island | Certifying, and diving any month |
Phuket in short
Phuket is the larger, better-connected base, and its reputation rests on trips that do not start there. The Similan Islands are a day trip or a liveaboard from Phuket rather than a Phuket dive site, and Mu Ko Similan National Park closes them annually for roughly five months. The Tourism Authority of Thailand's park listing gives 16 May to 14 October; reporting for 2026 gives slightly different days. Two official-side sources disagreeing is itself the finding: check the current year's announcement rather than trusting any single date, ours included. Book a Phuket dive week inside that window and you have booked somewhere else.
On the checking side Phuket is thinner than its size suggests. Of the 61 operators we list, 8 are in the Green Fins register, and all 8 hold an in-person assessment from the last twelve months: 1 Gold, 4 Silver, 3 Bronze. That is a real credential and it covers about one operator in eight.
Koh Tao in short
Koh Tao is small, dives all year, and is the cheapest place in the world to get certified: our Koh Tao guide puts a PADI Open Water course at around $340 and living costs at roughly $470 to $625 a month. It is a two-to-four-week island rather than a long base for most people, and it can feel small and party-heavy if you stay.
What it also has, and what surprised us when we counted, is the checking. 28 of its 58 operators are Green Fins members, 24 of them assessed in person within the last twelve months, and the tier spread runs 4 Gold, 18 Silver, 2 Bronze and 4 Digital. On raw operator count the two islands are level. On independently assessed operators Koh Tao has three times as many.
The honest take
If you are certifying, or if you are travelling between mid-May and mid-October, Koh Tao is the straightforward answer: it is cheaper, it dives every month, and more of its operators have had somebody visit them. Phuket earns its place when the Similans are open and you want a liveaboard, or when you want an island that is not only about diving. Both sit under the same Thai visa, so the decision is season and checking, not paperwork.
One thing neither island offers: not one of the 119 operators across both lists publishes which languages its instructors teach in. If that matters to you, it is a question for the shop and not for a register.
Which should you pick?
- Certifying, or travelling May to October: Koh Tao.
- Similan liveaboards, mid-October to mid-May: Phuket.
- If independent assessment matters to you: Koh Tao, 24 assessed operators against 8.
- Either way, ask about instructor languages before booking. Neither island publishes them.
FAQ
Is Phuket or Koh Tao better for diving?
It depends on the month and on what you want checked. Koh Tao dives year-round and carries far more independently assessed operators: 28 of its 58 are in the Green Fins register and 24 of those were assessed in person within the last twelve months. Phuket carries 61 operators of which 8 are in the register, all 8 assessed. Phuket's signature trips run to the Similan Islands, which the national park closes for roughly five months a year.
When are the Similan Islands closed?
Roughly mid-May to mid-October each year. The Tourism Authority of Thailand's park listing gives 16 May to 14 October; reporting for 2026 gives slightly different days. Because two official-side sources disagree, check the current year's announcement rather than trusting any single date, including ours. The Similans are a day trip or liveaboard from Phuket rather than a Phuket dive site, so the closure decides what a Phuket dive week can contain.
Which is cheaper to get certified in?
Koh Tao, and by a wide margin: our Koh Tao guide puts a PADI Open Water course at around $340 and living costs at roughly $470 to $625 a month. We have not confirmed course prices or boat prices for Phuket at a primary source, so we do not publish a figure for it. That is an absence in our research, not a claim that Phuket is expensive.
Does either publish which languages instructors teach in?
No. Not one of the 61 Phuket operators and not one of the 58 on Koh Tao publishes instructor languages anywhere we could read. If it matters to you, ask before you book; neither register carries it.
Sources
- The Similan closure, the Phuket register counts and the tier spread come from our own Phuket guide, which cites the Tourism Authority of Thailand's park listing and records where two official-side sources disagree: Phuket diving.
- The certification price, living costs and visa position come from our Koh Tao guide: Koh Tao for digital nomads.
- Operator counts, Green Fins membership, assessment status and tiers are read from our own operator lists, where every entry links to the register record it came from and carries the date it was read: Phuket operators, Koh Tao operators.
- How we work: editorial standards.