Gulf of Thailand, strange tides; high, low tides all day & night

strange tides can ruin holiday plans on any beach in the Gulf of Thailand

How to find the cheapest hotel rates on Thailand?
Easy – book the hotel directly – cut out all middlemen. We display all Thai beachfront hotels that GUARANTEE, in writing, to discount below the lowest online rates when guests book directly with the hotel.
See the resorts list on the left, then contact the hotel using the e-mail box on the hotel page. We put guests in direct contact with hotels, and take no commission.
We also sell DISCOUNT ROOM VOUCHERS, the cheapest rooms available on Thai beaches. But these are limited. Just click TOP DEALS above. Contact Jade for advice anytime:



These strange tides can have a BIG effect on a beach holiday here

Strange tides in the Gulf of Thailand interrupt visitor holidays much more than most people imagine. Who wants low tide all day, with wide expanses of sandbank exposed, and no water for hundreds of metres? Who wants the tide so high that it swallows the entire beach, leaving no sand for children to play in, nor sand for adults to sunbath on – all day long?
This unusual reality covers all beach destinations in the Gulf of Thailand, with negative effects on many visitors’ holidays. High tide lasts all through the day from November through March, with low water all night. Low tide runs all through the day from May to September, with high tide all night. The reversals are relatively quick, taking place in April and October. Strange? Indeed, even a little mysterious how the pull of the moon can be defied in this specific area. On Thailand’s Andaman coast the tides flow in perfect normality; four tides every 25 hours.
The difference it makes is significant, even critical in some destinations for visitors who plan to swim or snorkel, play in the sand or sunbathe on it. In places like Koh Chang, where the beaches are especially narrow, the sand disappears entirely at high tide, leaving little or no beach during the day for many months. In places where the water is rather shallow, like Koh Phangan, the water often recedes hundreds of metres, leaving seemingly endless sandbanks. Additionally, those wide expanses of sand often end at an offshore reef, where rock and dead coral rubble block people from getting to the water at all.
Spring tides, which fall every 14 days following the full and black moon phases, simply exaggerate the effect. These produce even high tides than usual – thus flooding even more of the beach – or lower tides, taking the water further out and leaving even more exposed sandbanks.
Those planning a beach holiday in a Gulf destination – with hopes of swimming, snorkelling, playing in the sand or sunbathing on it – should thus take note of the conditions they will find at different times of year. The height of the water and amount of available sand can make a big difference to a beach holiday, especially if children are involved.

how can Thailand defy moon power with just 2 tides, not 4, each 24 hours?

The moon, we all know, exerts gravity that pulls at and moves the earth’s oceans, creating four tides – two high and two low – every 24 hours. Each day thus sees both one high and one low tide on all beaches, with the night experiencing the same up and down ebb.
The strange tides of the Gulf of Thailand are a phenomena specific to enclosed bodies of water, with similar effects seen in the Persian Gulf, the Gulf of Mexico and Australia’s Gulf of Carpentaria.
The simplistic explanation is here: when water runs up and down a channel, and two waves flowing in opposite directions meet, there’s collision and mayhem. As an outgoing tide in the Gulf of Thailand runs south, it meets the next incoming tide flowing north; they clash and virtually cancel each other out. That principal is easy to understand, but the rest of the story – why do the tides last all day for part of the year, then quickly reverse – involves scientific formulae of enormous complexity. Two Japanese scientists who studied the Gulf of Thailand tidal flows, Tetsuo Yanagi and Toshiyuki Takao, came up with calculated explanations that took account of, among other things: bottom topography and friction against it; changing depths; the water’s ‘horizontal eddy viscosity’; the ‘Coriolis force’; the right angle turn in the middle of the Gulf and the semi-diurnal tidal wave. By applying complex mathematical formulas they came up with explanations that few on this planet would understand.
Interestingly, they discovered that during some periods the unusual tides were delivered to the upper Gulf in an anti-clockwise flow, while the southern part of the Gulf experiences clockwise flows at the same time. Complex? Indeed – and that’s about as much as we need to say to give a general overview.

these strange tides affect all major beach destinations in The Gulf of Thailand

Who wants low tide on the beach in front of your hotel room to last all day, with the water far out, and perhaps not even enough for splashing around in, let alone swimming? Alternatively, during other months you may have so much water all day that the beach is completely submerged, leaving no dry sand for you to lay a towel on, or for your children to play in.
Here is a brief run-down on how the major beach destinations in the Gulf of Thailand are affected by the strange tides.

Koh Chang: narrow beaches

The beaches of Koh Chang are so narrow that none show up in Google Earth’s satellite images of the island. All beaches down the west coast (that’s most of them) are shallow, leaving little water for swimming during the low tide months.

Interestingly, Koh Chang’s west coast beaches of Sai Khao, Ta Nam (Lonely Beach) and Kai Bae all have deeper water at the north end, with much wider sand too. This is caused by the action of waves and currents moving during the monsoon season, when the winds push them from south to north. The beach with the deepest water and best swimming conditions on Koh Chang, even at low tide, is Klong Kloi in the far south – but only the east side of the beach in front of the large, interesting resort called Koh Chang Boat Chalet .

Koh Kood: beautiful pristine beaches; but narrow and shallow too

Beach conditions here almost replicate those on nearby Koh Chang; narrow and shallow, all lying down the island’s west coast. Here too is a wider, deeper beach on the far south coast at Ao Phrao. The most popular west coast beach, Klong Chao, is lucky to be wider than average with plenty of sand remaining dry through the high tides. But most others here are underwater by day during the ‘foreign’ high season months (December - March), then quite dry during the rest of the year.

Koh Samui: a varied mix of wide and narrow, deep and shallow beaches

Koh Samui is big and diverse enough to have a good variety of beach conditions. While some beaches are quite narrow, and prone to disappearing at high tides, there are others that are exceptionally wide, keeping lots of dry sand at high tide.

The majority of Koh Samui’s beaches are quite shallow, and dry out during low tides. But there are several nice exceptions with enough water for swimming at all but the lowest spring tides. Maenam and Bophut Beaches are prominent in this lucky group, with relatively deep water that puts them among the best swimming beaches here. Long Lamai Beach is exceptionally shallow at the top end, and delightfully deep at the south end, making this perhaps the best swimming beach on the island. All beaches on the west and south coasts are both narrow and shallow, and suffer the negative effects of both high and low tides.

Chaweng Beach is not too narrow, and retains dry sand at all but the highest spring tides. The northern end, however, is particularly shallow, while the south end is significantly deeper and better for swimming at all tides.

Koh Phangan: offshore reefs & 100s of metres of dry sandbanks

Virtually all beaches on Koh Phangan are hemmed in by an offshore reef that virtually rings the island. This helps make them both narrow and shallow, and therefore subject to the negative effects of both high and low tides. The Full Moon Party beach of Haad Rin is somewhat wider and the thousands of revellers always have enough sand to party on. But the best swimming beaches on this island, by far, are the twin beaches at Thong Nai Pan, for this pair have no offshore reef and their sand runs smoothly into deeper water.

Koh Tao: sometimes too much water, sometimes not enough

Beaches along the south and west coasts of Koh Tao have offshore reefs, and are thus shallow – plus they all have narrow sand. Expect either too much water, or too much sand through most of the year. The three small bays on the east coast have no reefs and the water runs deeper. Only the southern two of these – Ao Leuk and Tanote Bay, as shown on our maps – have real sandy beaches. Both are quite wide and offer the best beach and swimming conditions on the island.

Hua Hin: beach walls that chase away the sand

Virtually all 30 kilometres of the Hua Hin and Cha-Am coastlines have been walled by homes, condos and resorts trying to extend their land as far seawards as possible. This destructive practice has made a huge ecological mess of the beaches here. The worst sections have lost most or all of their sand to wave erosion – a direct consequence of the wall construction. A few areas less affected by walls have been rewarded with more sand.

Many visitors to Hua Hin are disappointed to find their beachfront has little or no sand. If a nice sandy beach is important to you, do check carefully when seeking a hotel in this area. This website shows the beach in front of all resorts along this coast, and highlights the mess the beaches of Hua Hin and Cha-Am have become due to those destructive walls.
Pattaya: messy crowded beaches

Pattaya is the beach resort highest in the Gulf of Thailand. That’s not a great distinction, for this enclosed body of water is thoroughly polluted by the discards of tens of millions of Thais living north of here, with the pollution being channelled down in the various rivers that empty their unsavory contents into the top of the Gulf. However, this high in the Gulf the tides are not affected so directly by the meeting, and cancelling, of opposing tides. So while they follow the general high-low, seasonal shifts, Pattaya tides are even more complex.

During the daytime low tide – May through October – Pattaya’s beaches are not pretty. During the daytime high tide – November to March – they look much better, even if there is far less beach to be seen.

by John Everingham
######need advice about Thai beaches, beachfront hotels etc? try this for free.

Ask John E, the author here. He has photographed 1,100+ hotels on virtually every beach in Thailand with beachfront accommodation (and more in regional countries) over the past 30 years. “I try to answer all queries, and help as best I can.” E-mail:

hotels in this destination

that guarantee below-market rates

for direct bookings