# Possible to have a place in Ocean with no tides? **URL:** \ **Category:** Factual Questions\ **Created:** [October 19, 2014, 2:41pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804 "2014-10-19T14:41:06Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [October 19, 2014, 2:41pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/1 "2014-10-19T14:41:06Z")
I’m currently on phu quoc an island off the southern coast of Vietnam. I’ve been here two whole days and the sea level hasn’t changed in that time. To make it even stranger there is a sign on the beach saying that the sea is high and beach narrow between May-October and sea low and beach wide between November - April. And indeed the sea is constantly “high” up against the high tide mark right now. Is this possible? How? What kind if alternate dimension with mysterious extra moons have I slipped into? To be clear this island is in the gulf of thailand, it’s open to the ocean it’s not in a lake or in an enclosed bay. I’ve been to several other locations around the gulf of thailand and they had normal high and low tides. ---
**Author:** ![Greg\_Charles](https://avatars.discourse-cdn.com/v4/letter/g/839c29/32.png) [@Greg\_Charles](https://boards.straightdope.com/u/Greg_Charles)\ **Post date:** [October 19, 2014, 3:56pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/2 "2014-10-19T15:56:02Z")
Yes, it is possible. It’s called an amphidromic point. I’m not sure Phú Quốc qualifies, but that area does tend to have a small tidal range. Have fun there! I have fond memories of it. It’s where I learned to ride a motorbike a decade or so ago. ---
**Author:** ![Toastmaker](https://avatars.discourse-cdn.com/v4/letter/t/74df32/32.png) [@Toastmaker](https://boards.straightdope.com/u/Toastmaker)\ **Post date:** [October 19, 2014, 4:01pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/3 "2014-10-19T16:01:59Z")
_ **Possible to have a place in Ocean with no tides?** _ Not on this planet. All oceans and seas will have varying degrees of tidal effects. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 19, 2014, 4:02pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/4 "2014-10-19T16:02:19Z")
Here’s the tide table for nearby [Duong Gong.](http://www.tide-forecast.com/locations/Duong-GJong/tides/latest) It appears that over the last few days the tidal range has been only about 10 inches. Even a small amount of wave action would obscure that. In a week the tidal range will increase to about 3 feet, which will be more noticeable. The amplitude of tides is greatly affected by the configuration of the coast. Here in Panama, the tidal range on the Caribbean coast, which is mostly open to the ocean, is only about 2 feet, while only 50 miles away in the Gulf of Panama on the Pacific the tidal range is as much as 18 feet. ---
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [October 19, 2014, 6:35pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/5 "2014-10-19T18:35:04Z")
Even the Great Lakes have tides, though the level is more determined by wind direction > **[Do the Great Lakes have tides?](https://oceanservice.noaa.gov/facts/gltides.html)** > > Water levels in the Great Lakes change because of weather effects, not tides. Brian ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 19, 2014, 7:45pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/6 "2014-10-19T19:45:31Z")
Not only will the height of the tides vary, but a steeper coast will make them appear less significant, as well. ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [October 19, 2014, 9:08pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/7 "2014-10-19T21:08:21Z")
The tidal signal is made up of various harmonic components adding constructively and destructively. Among the most familiar components are the 12.5 hour lunar, 12-hour solar, monthly and semi-annual. For any one of these components, there can be regions where the amplitude is high and nodes where the amplitude is zero, thanks to interference patterns within a given body of water. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [October 19, 2014, 9:28pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/8 "2014-10-19T21:28:39Z")
Most of the aforementioned amphidromic points are a significant distance offshore, as you can see on the map provided in the wiki article: > **[Amphidromic point](https://en.wikipedia.org/wiki/Amphidromic_point)** > > An amphidromic point, also called a tidal node, is a geographical location which has zero tidal amplitude for one harmonic constituent of the tide. The tidal range (the peak-to-peak amplitude, or the height difference between high tide and low tide) for that harmonic constituent increases with distance from this point, though not uniformly. As such, the concept of amphidromic points is crucial to understanding tidal behaviour. The term derives from the Greek words amphi ("around") and dromo Amphi... Sri Lanka has one pretty close in, and you can see that this point on the east coast of Sri Lanka has a maximum tidal range of 1.3 feet: > **[Tide Times and Tide Chart for Kalmunai](https://www.tide-forecast.com/locations/Kalmunai/tides/latest)** > > Kalmunai tide times and tide charts showing high tide and low tide heights and accurate times out to 30 days. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 19, 2014, 10:02pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/9 "2014-10-19T22:02:59Z")
> [@coremelt](#): > > I’m currently on phu quoc an island off the southern coast of Vietnam. I’ve been here two whole days and the sea level hasn’t changed in that time. To make it even stranger there is a sign on the beach saying that the sea is high and beach narrow between May-October and sea low and beach wide between November - April. > > And indeed the sea is constantly “high” up against the high tide mark right now. > > Is this possible? > [@Greg\_Charles](#): > > Yes, it is possible. It’s called an amphidromic point. I’m not sure Phú Quốc qualifies, but that area does tend to have a small tidal range. Greg Charles is correct, even if not a complete answer. The area changes as the sign states because of the very complicated movements of the earth, moon and their relationship to the sun. > [@coremelt](#): > > How? What kind if alternate dimension with mysterious extra moons have I slipped into? It’s only amazing when you first learn about it, after that it can be frustrating because a lot of people simply will not believe it. I’m not kidding about that. [This image is a computer generated map](http://www6.cityu.edu.hk/see_mer/images/amphidromic.gif), showing the points of no tide (called nodes, amphidromic points), but they are not fixed, nor are all of them shown. It’s a very very very complicated system, and it changes all the time. What you are experiencing is an area where the complicated shifting amphidromes change yearly, which isn’t even the strangest thing about ocean tides. [http://www.tecplot.com/learning/plot-gallery/animations/?nggpage=2](http://www.tecplot.com/learning/plot-gallery/animations/?nggpage=2) [New Zealand tides](http://www.tecplot.com/wp-content/gallery/animations/tecplot_animation_new_zealand.gif), and Iceland both have a tide circling the island, so that there is a high tide on one side, and a low on the other. All the time. [Here is a look](http://159.226.119.58/aosl/article/2014/1674-2834-7-5-476.html) at how complicated ocean tides actually are. [Here is another image showing the nodes](http://aapgbull.geoscienceworld.org/content/97/5/799/F8.large.jpg). There are many many places in the ocean where there is no tide to speak of. Shorelines as well as out in the ocean. ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 19, 2014, 10:17pm UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/10 "2014-10-19T22:17:27Z")
> [@hibernicus](#): > > The tidal signal > [@yabob](#): > > Most of the aforementioned amphidromic points I did not see those replies before posting, or I would have included them in my response. The map graphics are not actual looks at what occurs, there are multiple factors, so the nodes are not as simple as the images show, nor does water always behave as theory would say. It’s very very very complicated, but the concept is sound. Ocean tides are nothing like what is taught showing two bulges following the moon around. The tides are giant circulating waves. ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [October 20, 2014, 12:39am UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/11 "2014-10-20T00:39:37Z")
Thanks for the info, what about the sign in my op claiming the tide is high for six months and then low for six months. How is that possible? ---
**Author:** ![mobocracy](https://avatars.discourse-cdn.com/v4/letter/m/0ea827/32.png) [@mobocracy](https://boards.straightdope.com/u/mobocracy)\ **Post date:** [October 20, 2014, 12:51am UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/12 "2014-10-20T00:51:19Z")
Do the tides have an affect in the middle of the ocean? Obvioulsy there’s no shoreline reference point so it may not matter, but does the surface level of the ocean actually increase or decrease with tides far from shore? ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 20, 2014, 1:04am UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/13 "2014-10-20T01:04:01Z")
> [@coremelt](#): > > Thanks for the info, what about the sign in my op claiming the tide is high for six months and then low for six months. How is that possible? Because as the earth changes over the year, the amphidromic systems change to follow the changes. Not being familiar with that location, I can’t say with any authority what is happening, but it’s quite possible, and based on science. There are some really strange things that happen with ocean tides. In that area, obviously the yearly cycle matters a lot. Which means it’s a solar issue, the changes are due to the earth changing it’s tilt, and distance from the sun. This happens every year. > [@mobocracy](#): > > Do the tides have an affect in the middle of the ocean? Obvioulsy there’s no shoreline reference point so it may not matter, but does the surface level of the ocean actually increase or decrease with tides far from shore? Yes, and if you look at the maps, you can see estimates of the change in the ocean surface height. At the nodes, there is no change. But everywhere else, it’s up and down. But, and this is cool, the height at sea is always very little. It’s where these giant circulating waves pile up, due to land masses, that we observe large changes. In the deep ocean, the maximum tidal change is about a meter at most. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [October 20, 2014, 1:16am UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/14 "2014-10-20T01:16:01Z")
> [@coremelt](#): > > Thanks for the info, what about the sign in my op claiming the tide is high for six months and then low for six months. How is that possible? It’s most likely due to changes in wave energy dependent on the season. The same thing happens on the coast of California: > [@](#): > > Southern California beaches undergo dramatic seasonal change due to a shift in wave energy. High-energy winter storm waves pull sand offshore, creating more narrow, cobbled beaches. Lower, gentle summer waves carry sand onshore, widening beaches. [http://ca-sgep.ucsd.edu/focus-areas/healthy-coastal-marine-ecosystems/explore-beach-ecosystems/sand-movement](http://ca-sgep.ucsd.edu/focus-areas/healthy-coastal-marine-ecosystems/explore-beach-ecosystems/sand-movement) Is it possibly related to the monsoon season in southeast Asia, where rainstorms (high energy waves) occur in the summer months and the winter months are dry (low energy waves)? > **[Monsoon](https://en.wikipedia.org/wiki/Monsoon#East_Asian_Monsoon)** > > A monsoon (/mɒnˈsuːn/) is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscillation of the Intertropical Convergence Zone (ITCZ) between its limits to the north and south of the equator. Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry p ---
**Author:** ![FXMastermind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fxmastermind/32/7289_2.png) [@FXMastermind](https://boards.straightdope.com/u/FXMastermind)\ **Post date:** [October 20, 2014, 1:28am UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/15 "2014-10-20T01:28:15Z")
Can’t locate a tide chart for that particular area. > **[Map of Tide Stations in Cambodia](https://www.tide-forecast.com/weather_maps/Cambodia)** > > Interactive map showing tide stations in Cambodia But based on the tide charts we can look at, that area really is a strange tide area. > **[Tide Times and Tide Chart for Kampong Saom](https://www.tide-forecast.com/locations/Kampong-Saom-Cambodia/tides/latest)** > > Kampong Saom tide times and tide charts showing high tide and low tide heights and accurate times out to 30 days. There are definitely nodes nearby, you can see this in the very changeable tides nearby. > **[Tide Times and Tide Chart for Vung Tau](https://www.tide-forecast.com/locations/Vung-Tau-Vietnam/tides/latest)** > > Vung Tau tide times and tide charts showing high tide and low tide heights and accurate times out to 30 days. Note the drastic difference in the tidal range. Of course the topography matters a lot as well. ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [October 20, 2014, 2:06am UTC](https://boards.straightdope.com/t/possible-to-have-a-place-in-ocean-with-no-tides/701804/16 "2014-10-20T02:06:18Z")
Ignorance thought. Many thanks