What is a tide?
Tides are the alternate rise and fall of the surface of the sea. They are caused by the attraction of the moon and sun, and occur twice a day. When the tide is high, there will be less of the beach visible than at low tide because the water level is higher:
Lyall Bay at high tide and low tide.
How do tides affect the beach?
Changes in the tide can affect the conditions in the water in a number of ways. They can change the wave action or cause rips and other currents to form.
For example, at some beaches spilling waves (where the top of the wave tumbles down the face of the wave) will occur at low tide, but as the tide rises and waves hit a steeper part of the beach they will become dumping waves (where the wave breaks with tremendous force), which can be very dangerous. Find out more about wave types.
Tidal currents also occur at sea, sometimes very close to the shore. Tide height will affect the beach and waves, but it will also affect the movement of objects floating at sea. This is particularly important in search and rescue operations because it could help identify the likely location of a lost person or vessel at sea.
It is also important that you know when high and low tides occur as at some beaches you could become cut off from access ways by a rising tide.