East then south, from the climbing walls at Railay to the cave diving at Koh Haa. The route for a group that includes certified divers.
The eastern side of the bay is a different landscape from the Phuket side: the karsts get taller, the water gets clearer as you go south, and the traffic thins out past Krabi.
This route earns its length in the second half. Koh Haa is five small islands arranged around a natural lagoon with a submerged cathedral chamber and a vertical chimney in the limestone, and it is the best cave diving in Thai waters. Koh Rok, further south, is two uninhabited islands with a white sand channel between them.
It crosses two national parks, which means two separate per-person fees. An operator who folds both into the advance provisioning allowance without naming them is not overcharging you, but they are making it harder for you to compare their quote with anyone else's.
Leave Ao Po and cross the bay east. The Krabi Koh Hong has a wide entrance into its lagoon, so the tender goes in under power at any tide. Anchor off the east beach for the night.
Short hop south to the Railay peninsula. Climbing on the walls above the beach for anyone who wants it, the cave shrine at Phra Nang for everyone else. The anchorages here are open to the west, so this is a northeast-season stop only.
Down the coast and across to the Phi Phi group, using the northeast anchorages rather than the town. This is the day the route leaves the sheltered bay behind.
Run southeast to Koh Haa and pick up a park mooring inside the ring of islands. Two dives if the group is certified, snorkelling on the shallow edges if not. The lagoon shelters from most headings, which makes it a rare comfortable overnight this far out.
Morning at Koh Rok in the sand channel between the twin islands, then the passage back north. This is the longest single leg of the itinerary and most crews start it by early afternoon.
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 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.
The anchorages are open to the west, so this is a northeast-monsoon stop only. Between May and October the swell runs straight in and the whole peninsula becomes a landing you would not want to make with guests.
Do not plan to anchor overnight in Tonsai. It is a working ferry harbour with a hard bottom in places, heavy traffic until late and a swell that wraps in from the southwest. Yacht crews use Loh Bagao or Laem Tong and run the tender the ten minutes to town if guests want the evening ashore.
Koh Haa is the diving reason to route south rather than west. If the group includes certified divers, an itinerary through Koh Haa and Koh Rok gives them better water than the Phi Phi loop, without the five-day passage that the Similans demand.
Rok is the reward for going further than the standard week does. It is roughly a full day's passage from Phuket and only makes sense on an itinerary that is already working south through Phi Phi and Lanta, which is why it appears on five-day southern routes and almost never on three-day ones.
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.
Five-night skippered, Phuket and Krabi handover
Crewed catamaran, seven-night version adding Koh Rok and Lanta
Sailing itinerary, monohull, Ao Po round trip
Four-night version, Krabi only
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Source: Operator itineraries, national park fee schedules. Checked 6 September 2026. Distances are planning figures and the coastlines on the chart are simplified. Neither is for navigation.