Understanding waves, tides and currents

Understanding tides and currents will help you stay safe if you like to go swimming in the sea. Find out how to identify safe waves to swim in and how to spot a rip current.

How to identify a wave

When swimming, surfing or bodyboarding, it's helpful to understand the different types of waves so you can decide whether to go out or stay ashore.

Spilling waves

Spilling waves are the safest to swim in - they appear when the top of the wave falls down the front of itself.

Surging waves

Surging waves don't break and can easily knock someone over, dragging them out to sea.

Dumping waves

Dumping waves break with great force in shallow water. They are powerful and dangerous and normally occur at low tide. Avoid going into the sea when you see dumping waves.

Beware of dangerous waves

Always watch for dangerous waves, like surging waves or dumping waves and never think it's safe to wave-dodge. The sea is unpredictable and what looks like fun could end in tragedy. Large waves could take you out to sea in a matter of seconds.

You should also beware of rough or choppy water - it can sap your strength and make you too tired to swim. If the water is rough, get out of the sea and wait until it is calm enough to go in again.

Know the tide times

It's important to check the tide times for the beach you're visiting. The tide comes in and out twice a day. This means the beach that you arrived at in the morning can be a very different place only a few hours later. For example, if you walk out at low tide, you may not be able to return if the tide comes in and the water rises.

If you're at the beach with children, make sure they are not playing somewhere that could be cut off if the tide comes in.

You can find out the tide times using EasyTide.

Recognise the signs of a rip current

Always watch for signs of rip currents (also known as riptide). A rip current is water that is:

  • discoloured
  • choppy
  • foamy
  • filled with debris

Some rip currents are so strong they can carry swimmers away from shore before they know what is happening.

What to do in a rip current

If you are caught in a rip current, remember the three Rs:

  • relax - stay calm and float (don't swim against the current as you will get exhausted)
  • raise - raise an arm to signal for help and if possible shout to shore
  • rescue - float, wait for help and don't panic (people drown in rips because they panic)

Always obey directions from the lifeguard.

If you think you can swim out of the rip, swim parallel (alongside) the shore instead of towards it. Once the rip stops pulling you, try to swim to shore. If you feel you can't make it, wave for a lifeguard's help.

Watch out for underwater hazards

There are some dangers at the beach that you can't always see. The depth of the water will change from hour to hour and hide things like rocks, piers and breakwaters (concrete structures in the sea).

Don't jump into the unknown - tombstoning

Tombstoning is a high-risk, unregulated and unsupervised activity that involves jumping or diving from a height into water. Tombstoning is dangerous because:

  • water depth changes with the tide so the water may be shallower than it seems
  • you may not see submerged objects, like rocks
  • strong currents can sweep you away

Before you are tempted to jump:

  • look for any hazards in the water
  • check the water's depth - as a rule of thumb, it should be at least five metres deep for a jump from a height of 10 metres
  • make sure there's a way to get out of the water
  • don't let alcohol, drugs or peer pressure affect your judgment

If you see someone in trouble

If you see someone in trouble, phone 999/ 112 and ask for the coastguard.

These numbers apply in the Republic of Ireland too.

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