Krabi tides – how low and high water shape your island day

On the Andaman coast there are usually two high waters and two low waters a day, so a little over six hours lie between high and low. The times shift later by almost an hour every day – if low tide is at 9 am today, it will be around 10 am tomorrow.

The tidal range, the difference between high and low water, is very noticeable in Krabi and can reach several metres during spring tides. Beaches that are narrow at high tide become wide at low tide; bays navigable at high tide partly dry out at low tide.

Around new moon and full moon, the sun and moon pull together – these are spring tides. High water rises especially high and low water falls especially low. For sandbars it is the best time. Around half moon the differences are smaller; these are called neap tides.

As a rule of thumb for the main destinations from Ao Nang:

Tide tables for Krabi or Ao Nang are available online and in apps. They show the times of high and low water for each day and the height in metres. Not only the time matters but also the height: a low water with a very low value means a particularly large sandbar.

Note that tables refer to different gauging points and local values can differ slightly. That is why a captain’s experience is worth more than any app.

Tides also mean current. Between high and low water, a lot of water flows through channels and around island tips – exactly where snorkellers like to go. Just before and after the turn of the tide, the current is usually weakest.

In lagoons with narrow entrances, such as Koh Roi, a rising tide can make the way back harder. Follow the crew’s timing and only swim in noticeable current with a life jacket.

For snorkellers, the water level is an underrated factor. At very low water some reef flats are so shallow that you can barely swim over them without touching coral. At higher water you have more clearance and the fish are more relaxed.

Visibility is linked to the tides too: clear water flowing in from the open sea often improves it, while water ebbing out of mangroves and river mouths can make it worse. That is why a local captain picks the reef side based on the current flow.

The art is ordering the stops so each place is visited at the right water level – ideally outside group times. If low water is early in the morning, for example, the day starts at the Tup sandbar and ends at the Hong lagoon on a rising tide.

Group tours with fixed schedules can barely respond to this. A private boat, by contrast, plans each day fresh. That is exactly why the same island can feel completely different on two different days.