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About the tides
what causes them?
updated Nov 09
if you learn only 3 things about them ...
The tide height is not the same every day.
Low spring tides in Singapore usually happens before sunrise or after sunset.
Low spring tides happen near the new and full moon.

Our shores are submerged most of the time. Safe and wet underwater, amazing plants and animals live out their lives unseen.

The non-diver and casual visitor can only have a 'dry' and easy view of this rich intertidal zone when it is exposed during low spring tides.

The lower the tide, the larger the expanse of shore that is exposed. The coastal area affected by the tides is called the intertidal zone.

Isn't there a low tide every day? Yes, it's true, there is a 'low' tide every day. Singapore has two low tides and two high tides a day. The height of the tide is not the same every day. High and low tides do not happen at the same time every day, and the highest and lowest tide level change every day.

What affects the tides? Among the factors that can affect tide height are:

  • Gravitational pull of the moon.
  • Gravitational pull of the sun (although much further away, the sun is gianormous).
  • The rotation of the earth (the way your laundry in a spinning washing machine moves outwards).

Spring Tides: During a full moon or new moon, the moon and sun are lined up. Their combined gravitational effect results in an extra high and extra low tide. This is called a spring tide because the water appears to spring up.

Neap Tides: At a quarter moon or three-quarter moon, the sun's gravity works at right angles to that of the moon. This results in a smaller difference in height between the low and high tide. This is called a neap tide.

There's an animation of the tides on the NOAA website.


What's so special about a low spring tide? During a super low tide, we can get a quick glimpse of a part of the shore that is seldom exposed. Also, usually a larger area of the shore is exposed, since the low tide is a lot lower. So there is more to see in terms of variety and area uncovered. But remember the 'spring' part of this low tide: so the tide moves fast and the window of low tide is usually short, about an hour at most. Guided walks on our shores are usually held during low spring tide.

In the photo of the natural shore of Sentosa (on the left) at low spring tide, you can see the mid-water mark as the dark portion on the natural cliffs. The area exposed at low spring tide is quite different from that at higher tides. It can also be dangerous to go at the wrong tide, or to be unaware of the turning tide as you might get trapped.

Not all shores can be visited at the same tide level. Some shores in Singapore require lower tides than other shores for a safe and enjoyable visit. A shore with a gentle gradient means a larger area is affected by the tides resulting in a wider intertidal zone that can be explored for a longer time during low tide. While a steeper sloping shore means there is a narrower intertidal zone which is not exposed for long during low tide.

It's thus important to go with experienced people and with shore guides. You will be safer, and also see and learn more about our shores.
Here's more about preparing to visit our shores.

Other things to note about our tides: In Singapore, spring tides usually occur over a few days twice a month and usually for only a few hours each time. The low spring tide usually happens before sunrise around April to August (at about 2-3am), and then after sunset in October to February. Often, there are no low spring tides in September and in March.

Low spring tides don't necessarily happen on weekends.

Low tides don't happen at the same time every day. This is because the moon takes more than 24 hours to go around the Earth. So the low (and high) tide shifts by about 50 minutes every day.

The tides can differ from predictions depending on the winds (which can raise water levels) and the barometric pressure (the pressure of the miles of atmosphere on the sea level).

If we go at a neap tide, will we see nothing? There is always something to see on our shores at any tide. For example, on rocky shores, the mangroves and coastal forests. High tide is when you are most likely to see fascinating animals such as otters, crocodiles, sea turtles, fishes and more. See the Adventures with the Naked Hermit Crabs blog for some sightings during their free Chek Jawa boardwalk tour which is conducted at any tide. Here more FAQs about visiting our shores.

Changing views of Chek Jawa
as the tide falls to a low spring tide.




Sentosa: a dangerous shore to visit
if you are unfamiliar with the tides.
The dark band marks the mid-water tide line.


The Chek Jawa boardwalk:
enjoyable and safe at any tide!

Online tide tables for Singapore

Links

www.flickr.com
FREE photos of intertidal landscapes . Make your own badge here.
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