87.24 sq km and two tambon on one island — Koh Yao Yai in the north, Phru Nai in the south, about 6,311 people in Phru Nai alone as at May 2564. A vehicle ferry from Rassada and speedboats from Bang Rong, first 07.30, last 17.40. No hospital: the district’s only one is on Koh Yao Noi, ten minutes across a channel. Power arrives by submarine cable from Ao Po in Phuket. Hotels and condominiums are capped by the Royal Gazette at 79 rooms, 16 metres, under 4,000 sq m.
One island, two tambon - and why that matters
Start with the thing most writing about these islands gets wrong. Amphoe Koh Yao has three tambon — Koh Yao Noi, Koh Yao Yai and Phru Nai — and it is tempting to read those as three islands. They are not. Two of the three sit on Koh Yao Yai: Tambon Koh Yao Yai across the north and Tambon Phru Nai across the south. The district also runs four local authorities, because Tambon Koh Yao Noi is split between a town municipality and an SAO. If you are searching land records, health facilities or planning rules, the tambon name is what the document will use, and it will not tell you which island you are on.
The Department of Marine and Coastal Resources puts the island at 87.241 sq km in the national island register, making it Phang Nga’s second largest after Koh Phra Thong, and more than twice Koh Yao Noi’s 36.140. The two municipalities give their own administrative areas as 43.75 sq km for Koh Yao Yai, across four villages, and 50.79 sq km for Phru Nai. Those are jurisdictions, not land surveys, and should not be compared directly with the DMCR figure.
Distances are short but the geography is awkward. Koh Yao Yai municipality is 4 km from the district office and 48.5 km from Phang Nga town. Phru Nai is about 15 km from the district office — a journey that means crossing the 2.3 km Chong Lat channel, about ten minutes in a hired boat, then roughly 12 km of road on the far side. The district office is on Koh Yao Noi. There is no bridge.
Getting there - the one Koh Yao crossing that is officially documented
Across the whole of Koh Yao district, exactly one government body publishes anything resembling a timetable, and it is Phru Nai municipality, in its own local development plan. That document is the reason this page can tell you when the boats run and the Koh Yao Noi page cannot.
| From | Arrives | What runs |
|---|---|---|
| Bang Rong pier, Pa Khlok, Thalang, Phuket | Khlong Hia pier, Tambon Koh Yao Yai | Speedboats and wooden boats. First boat 07.30, last boat 17.40, with departures nearly every hour |
| Chiaravanich pier, Rassada, Mueang Phuket | Loh Jaak pier - or Ban Laem Yai in heavy seas | Ferry and speedboat. The ferry carries four-wheel vehicles and small six-wheel trucks. The municipality states that when wind and waves are strong the boat berths at Ban Laem Yai instead |
| Tha Len pier, Khao Thong, Mueang Krabi | Khlong Hia and Chong Lat piers, Tambon Koh Yao Yai | Wooden boats |
Two details in there deserve pulling out. The Rassada ferry carries vehicles — four-wheel cars and small six-wheel trucks — which is why Koh Yao Yai has a road culture that Koh Yao Noi does not, and why moving a household here is a different proposition. And the municipality writes the bad-weather rule into its own plan: when wind and waves are strong the boat berths at Ban Laem Yai rather than Loh Jaak. That is the honest, documented shape of monsoon disruption on this island — not cancellation, but a different pier and a longer road at the far end.
Alongside the municipal document there is one operator publishing its own timetable for the Rassada crossings. It names its own boats and its captains’ telephone numbers, which is why we are willing to show it, but it carries no company registration, no tourism licence number and no date, so treat it as indicative and confirm before you travel. It publishes no fares.
| From | To | Depart - arrive | Vessel |
|---|---|---|---|
| Phuket (Chiaravanich) | Laem Yai | 08.30 - 10.00 | Ferry |
| Phuket (Chiaravanich) | Laem Yai | 09.00 - 09.30 | Speedboat |
| Phuket (Chiaravanich) | Loh Jaak | 10.00 - 10.30 | Speedboat |
| Phuket (Chiaravanich) | Loh Jaak | 11.30 - 12.00 | Speedboat |
| Phuket (Chiaravanich) | Laem Yai | 14.00 - 15.45 | Ferry |
| Phuket (Chiaravanich) | Loh Jaak | 17.00 - 17.30 | Speedboat |
| Loh Jaak | Phuket (Chiaravanich) | 06.30 - 07.00 | Speedboat |
| Laem Yai | Phuket (Chiaravanich) | 07.30 - 09.00 | Ferry |
| Loh Jaak | Phuket (Chiaravanich) | 16.15 - 16.45 | Speedboat |
The shape of it: the vehicle ferry takes about an hour and a half, the speedboats about thirty minutes, and the last boat off the island in this operator’s own list is 16.15. Nothing runs in the evening.
No hospital, and what that actually means
Phang Nga’s provincial health office lists one community hospital for the entire district — Koh Yao Chaipat — and it is on Koh Yao Noi. Koh Yao Yai, at more than twice the size and with the larger population, has health-promoting hospitals only: one for Tambon Koh Yao Yai covering Khlong Hia, Chong Lat, Ya Mi and Khlong Bon, and two in Tambon Phru Nai.
Phru Nai municipality publishes the staffing of its two stations, and the gap between them is the practical story of living at different ends of an 87-square-kilometre island. The Phru Nai station has a director, a doctor, four professional nurses, a public health academic, a pharmacy technician, three Thai traditional medicine practitioners, a dentist, a dental assistant, a physiotherapist and five general staff. The Loh Poh station has two people: a public health academic and a community public health officer.
What we could not find, and it is the important one. No government document we could reach names the mainland hospital that receives a Koh Yao referral, or describes how a patient is moved — by boat, by which boat, or whether any air asset serves these islands. We are not naming a hospital from general knowledge. If you are moving here with a condition that may need urgent care, this is a question to put directly to the Phang Nga provincial health office before you commit.
Power by submarine cable, water from the ground
Phru Nai municipality records that the island’s electricity is supplied from the Thalang district electricity authority in Phuket, carried by submarine cable from Ban Ao Po in Phuket, landing at Laem Hia in Tambon Koh Yao Yai and distributed onward from there. Both Koh Yao islands sit on the end of that link. It is a genuine single point of failure, and we found no official record of how often it fails, so we are stating the architecture rather than the reliability.
The same municipality is honest about what is unfinished: street lighting does not yet run along every road in the communities, and the distribution area has not yet reached every household. Water comes from weirs, check dams and reservoirs fed by natural sources, plus village boreholes — local supply rather than anything piped from the mainland. On the neighbouring island the SAO states flatly that its own water runs short in the dry season, which is the right expectation to carry here too until a specific house proves otherwise.
On connectivity, the municipality counts masts village by village: three in Moo 1, one in Moo 2, two in Moo 3, two in Moo 4, and eight public telephone boxes. It lists none for Moo 5, Moo 6 or Moo 7. A mast elsewhere can still reach a village, so that is not proof of a dead zone — but it is the municipality’s own document pointing at which end of the island to test before signing anything.
Who lives here, and the honest gaps
Phru Nai municipality counted 6,311 people in the southern tambon as at May 2564, at a density of about 125 people per square kilometre, across 2,205 houses averaging three people each. Most residents are Muslim, and the municipality records 15 mosques in its area. Schooling runs deeper here than on many Thai islands: three primary schools, one running primary to M.3 at Ban Phru Nai, one running primary to M.6 at Ao Kaphor, two childcare centres and a non-formal education centre. Ao Kaphor and Koh Yao Wittaya on the other island are the district’s only two schools that reach M.6.
There is a post office in Moo 2. Phru Nai’s plan lists no bank in the tambon at all — the district’s only two, both state-owned, are on Koh Yao Noi. And the postcode quirk worth remembering: Phru Nai uses 83000, a Mueang Phuket code, and the municipality explains that this is because getting things to and from Phuket is quicker than the alternatives.
- Any fare, from any acceptable source — no government fare notice and no operator fare page exists for these crossings.
- A current population for Tambon Koh Yao Yai, the northern municipality. It publishes area and village sizes but no population, so there is no whole-island figure on this page.
- The schools in Tambon Koh Yao Yai. We could not locate that council’s development plan, so the school list above covers Phru Nai only.
- The mainland referral hospital, and how a patient is transferred off the island.
- Any NBTC coverage or speed statement naming these villages, and any electricity reliability record for the submarine cable.
- The general shoreline setback for ordinary buildings, which sits in the annex to the 2568 notification that we have not transcribed.
Frequently asked questions
Yes to the car, and this is the practical difference between the two Koh Yao islands. Phru Nai municipality publishes three sea routes in its own development plan. From Bang Rong pier in Phuket there are speedboats and wooden boats, first boat at 07.30 and last at 17.40, running nearly every hour, berthing at Khlong Hia. From Chiaravanich pier at Rassada in Phuket there is a ferry that carries four-wheel vehicles and small six-wheel trucks, plus speedboats, berthing at Loh Jaak - and the municipality adds the detail that matters in bad weather: when wind and waves are strong, the boat berths at Ban Laem Yai instead. From Tha Len in Krabi there are wooden boats to Khlong Hia and Chong Lat. Separately, a boat operator's own timetable page shows the vehicle ferry running Laem Yai to Phuket in about an hour and a half and the speedboats doing Loh Jaak in about thirty minutes, with a first departure off the island at 06.30 and a last at 16.15. That operator names its own vessels and its captains' phone numbers, but shows no company registration, no tourism licence and no last-updated date, so we present it as operator-published and unaudited. Nobody publishes fares from a source we would rely on.
No. The whole of Koh Yao district has one community hospital, Koh Yao Chaipat, and it is on Koh Yao Noi. What Koh Yao Yai has, per the Phang Nga Provincial Public Health Office, is health-promoting hospitals: one for Tambon Koh Yao Yai serving the four villages of Khlong Hia, Chong Lat, Ya Mi and Khlong Bon, and two in Tambon Phru Nai. Phru Nai municipality publishes the staffing of its two, and the contrast inside them is worth seeing. Phru Nai's station has a director, a doctor, four professional nurses, a public health academic, a pharmacy technician, three Thai traditional medicine practitioners, a dentist, a dental assistant, a physiotherapist and five general staff. The Loh Poh station has two people: a public health academic and a community public health officer. So the level of care available depends on which end of a long island you are at, and anything serious means a boat - either the ten-minute channel crossing to the hospital on Koh Yao Noi, or Phuket. We could not find any government document naming the mainland referral hospital or describing how a patient is moved, and we are not going to guess it.
Because the post is quicker that way, and the municipality says so outright. Tambon Phru Nai uses postcode 83000, which is Mueang Phuket's, and Phru Nai municipality explains in its own development plan that this is because transport and communication with Mueang Phuket district are more convenient and faster than the alternatives. Koh Yao Noi uses 82160, a Phang Nga code. It is a small administrative detail that tells you the real orientation of the island: legally it belongs to Phang Nga, but functionally it faces Phuket, which is also where its electricity comes from and where its residents go for a hospital of any size.
The power comes from Phuket, through the sea. Phru Nai municipality records that electricity is supplied from the Thalang district electricity authority in Phuket, carried by submarine cable from Ban Ao Po in Phuket, landing at Laem Hia in Tambon Koh Yao Yai and running south from there. That is a single point of failure for the whole island, and worth knowing before you commit to a long stay - though we found no official record of outage frequency. The same plan is candid that the network is not finished: street lighting does not yet cover every road, and the distribution area has not yet reached every household. Water is local rather than piped from the mainland - weirs, check dams and reservoirs drawing on natural sources, plus village boreholes. For an island of 87 square kilometres with drought listed as a live concern across this coast, that means water availability is a house-by-house question, not an island-wide guarantee.
More than on Koh Yao Noi, but not much more. The Ministry of Natural Resources and Environment's notification of 27 March 2568, in the Royal Gazette, prohibits hotels, apartment buildings and condominiums throughout Koh Yao district, then permits them back within stated limits. For Tambon Koh Yao Yai and Tambon Phru Nai those limits are no more than 79 rooms, no more than 16 metres in height, and a combined floor area across all buildings of under 4,000 square metres. Koh Yao Noi gets 12 metres for the same 79 rooms, so the larger island has four extra metres and nothing else. Height is measured from the construction ground level to the highest part of the building. Anything of 11 to 49 rooms must additionally meet the technical requirements annexed to the notification. The notification runs five years from 28 March 2025 to 27 March 2030. All three tambon also sit inside the notification's mangrove conservation zone, and DMCR's island register records Ao Phang Nga National Park as the responsible unit for the island. BAANLYY is a listing portal, not a law firm; this is not legal advice.
Probably in the north, and we would ask hard questions about the south. There is no NBTC coverage statement for these villages that we could obtain, and no speed figures anywhere official. What exists is Phru Nai municipality's own infrastructure count, mast by mast: three masts in Moo 1, one in Moo 2, two in Moo 3, two in Moo 4, and eight public telephone boxes. It lists no mast at all for Moo 5, Moo 6 or Moo 7 - Ban Khlong Din Niao, Ban Ok and Ban Loh Pared. That is not the same as saying there is no coverage in those villages, because a mast elsewhere can reach them, and we will not overstate it. But if you are choosing where on this island to live and you need reliable connectivity, the municipality's own document is telling you which end of it to test first.
Related guides
- Koh Yao Noi — the smaller island with the district’s only hospital, and a tighter 12-metre building limit.
- Phang Nga — the province, and the bay these islands sit in the middle of.
- Phuket — where the ferry, the power cable and the postcode all point.
- Krabi — the third mainland pier, at Tha Len.
- Foreign condominium ownership — the framework, where the law caps a building at 79 rooms.
- Leasehold versus freehold — what a foreign buyer can actually hold.
- Retiring in Thailand — the route that most often brings people to an island this quiet.
- Island living in Thailand — how the islands differ on the things that decide a move.
The island you can drive onto
Koh Yao Yai is the rare Thai island where a household move does not mean leaving the car behind. If that changes the maths for you, look at what is listed around the bay.
Sources & References
- Phru Nai Subdistrict Municipality - its own local development plan (2566-2570, first revision 2566), which publishes the three sea routes to the island with a first boat at 07.30 and a last boat at 17.40 from Bang Rong, the rough-weather switch from Loh Jaak to Ban Laem Yai, the submarine power cable from Ban Ao Po in Phuket, the mast counts by village, the two health-promoting hospitals and their staffing, the schools, the municipal area of 50.79 sq km and a population of 6,311 as at May 2564
- Royal Gazette, Vol. 142, Special Part 152 Ngo, 27 March 2568 - the Ministry of Natural Resources and Environment notification on environmental protection areas and measures for seven Phang Nga districts including Koh Yao. Clause 7(3)(b) permits hotels, apartment buildings and condominiums in Tambon Koh Yao Yai and Tambon Phru Nai only at no more than 79 rooms, no more than 16 metres and a combined floor area under 4,000 sq m; clause 20 gives a five-year term. Figures read from the gazette page images
- Koh Yao Yai Subdistrict Municipality - its own basic information page, giving the municipal area of 43.75 sq km or about 27,282 rai, the four villages with their areas in rai, and the distances of 4 km to the district office and 48.5 km to Phang Nga town
- Department of Marine and Coastal Resources - the national island register for Phang Nga province, which gives Koh Yao Yai at 87.241 sq km, names it the province's second largest island after Koh Phra Thong, and records Ao Phang Nga National Park as the responsible unit
- Phang Nga Provincial Public Health Office - the provincial list of facilities in its own service, which shows one community hospital in the district, on Koh Yao Noi, and health-promoting hospitals rather than a hospital for Koh Yao Yai's villages
- Koh Yao Center Group / Koh Yao Marina - a boat operator's own published timetable for the Phuket to Koh Yao Yai crossings from Chiaravanich pier, naming its own vessels and its own captains' telephone numbers. It carries no company registration, no tourism licence number and no date of last update, so we treat it as operator-published but unaudited
- Community Development Department, Koh Yao district office - the district's own record that it became a full district on 1 January 2531 and holds four local authorities across three tambon
- Thai Meteorological Department - the national monsoon calendar: the southwest monsoon over Thailand from about mid-May to mid-October, the northeast monsoon from about mid-October to mid-February
Primary and official sources are cited above. Government rules, fees and procedures in Thailand change over time and vary by office; always confirm current requirements with the relevant authority before relying on them. BAANLYY never takes paid placement in editorial content.
