Tides
Unlike most places which have two tides each lunar day, Koh Mak has only daily high tide and one daily low tide; with the second tide effectively cancelled out by the size and geometry of the Gulf of Thailand. Still, it’s not uncommon for the tidal range at Koh Mak to be 1 meter or more. As a relatively flat island, this means that low tides on Koh Mak play host to wide (and largely deserted!) beaches, while at high tide many of these same beaches disappear almost completely. The nearest tidal buoy to Koh Mak is located at Llot Cone, Cambodia, for which this site provides a very nice and simple to use tidal chart: https://tides.mobilegeographics.com/locations/3557.html
Wind, Weather, Waves and more…
There’s no doubt weather comes and goes, so when visiting Koh Mak—or anyplace else, for that matter—it’s nice to have some idea of what to expect. Everyone has their own favorite weather site, and Windy.com is mine. Not only is Windy fast, free, lean and completely ad-free, it also provides real-time data for things like wave direction, length & height; sea temps; wind speed and direction, cloud cover and much more. If you’re headed to the beach for a swim, it helps to know which side of the island is currently the windward side, and which is the leeward. And if you’re going boating, sailing, snorkeling or diving, you can have a good idea of what winds, waves and sea temps to expect. Check it out: https://www.windy.com/?11.827,102.484,12