The itinerary that exists because Phuket has two coasts: when the southwest monsoon closes the west, the bay to the east stays workable.
From May to October the southwest monsoon puts swell on the whole west coast of Phuket and the crossings to Phi Phi and the Rachas become uncomfortable or unwise. Most of the charter fleet leaves or lays up, and most operators simply stop selling.
What is left is real, though, and hardly anyone explains it. Phang Nga Bay sits in the wind shadow of Phuket itself. The island takes the southwest, and the water behind it stays workable through most of the season. The anchorages at Koh Hong, Koh Yao and the eastern karsts keep functioning, and the bay is greener and almost empty.
Two honest caveats. The rain is real, and it arrives in heavy squalls rather than in drizzle, so a day can lose an afternoon. And September is the wettest month of the year in Phuket, which is why this route is listed for May, June and October rather than for the whole monsoon.
Straight into the lee. The west-coast anchorages at Koh Yao work in a southwesterly, which is exactly the reverse of the high-season pattern.
North into the bay. In the green season Koh Hong on a weekday can be empty, which never happens in February.
The caves do not care about the weather, only about the tide. This is the day that is unaffected by the season.
The eastern side of the bay is still sheltered water. Railay is not: the swell runs straight into those anchorages from May onwards, so the route stops short of it.
The value of doing this route on a yacht rather than on a day boat is control over the clock and the tide. Most of it comes down to these.
This is the standard answer to the question of where to sail between May and October. The bay east of Phuket sits in the lee of the island through the southwest monsoon, and Koh Yao is at the centre of that lee.
The tunnel into the lagoon is tide-dependent, not weather-dependent. Around high water the headroom disappears and the entrance closes. Ask the crew for the day's tide window before planning the afternoon around it, because the window moves about fifty minutes later each day.
The low caves only open around low water and close entirely on a big spring tide. If your itinerary has one fixed day in Phang Nga, the crew will pick between Panak and Hong based on the tide, and pushing them to do both on the wrong tide gets you neither.
This island sits in a different national park from Phang Nga, with a separate fee that is charged separately. An itinerary that crosses from Phang Nga into the Krabi group in one week pays two park fees per person, and a good operator itemises both rather than folding them into the APA without saying so.
No two operators run an identical itinerary. The variant is the useful part: a shorter version has dropped a destination, and it is almost always the furthest one.
Green-season skippered charter, reduced rates May to October
Bareboat and skippered, east-coast itineraries only
Short green-season charters, weather-dependent routing
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Lagoon
The workhorse of the Phuket bareboat fleet. Four cabins, eight berths, shallow draught for the limestone anchorages, and simple enough that a competent crew can run it without a skipper.
from $6,500
per week
Phuket Yacht Haven
Lagoon
A metre longer than the 42 and noticeably more comfortable for eight adults, with the flybridge helm that has become the standard layout in the charter fleet.
from $8,500
per week
Phuket Yacht Haven
Leopard Catamarans
The house catamaran of the global bareboat brands, built for charter service rather than adapted to it, with a forward cockpit that is genuinely useful at anchor in the tropics.
from $10,500
per week
Phuket Yacht Haven
Source: Andaman Sea seasonal guidance, operator low-season programmes. Checked 6 September 2026. Distances are planning figures and the coastlines on the chart are simplified. Neither is for navigation.