Coastal conditions - what do you usually see at the beach?

Waves

The coastline can be affected by various sea conditions mainly generated by the wind. It generates swell by blowing across the surface of the sea and you can see this as the rolling motion of the ocean.

Swell is usually associated with movement of only the upper level of ocean. As the swell gets closer to the coastline and the ocean floor becomes shallower, it forms the waves that you see crashing on the shoreline.

Sometimes this has spectacular effects such as the pipeline in Hawaii.

The size of the waves depends on:

How strongly the wind is blowing - the stronger the wind, the bigger the waves.
How far the wind blows - the farther the wind blows over the ocean, the larger the waves.
How long the wind blows - the longer the wind blows over time, the larger the waves.

Wave forms

Waves can take on three forms depending on the shape of the ocean floor at the coastline. Look at the images below.

Plunging waves break with tremendous force, usually in shallow water. They are dangerous to swimmers and surfers.

This is an example of a plunging wave.

Spilling happens when the top of the wave tumbles down the face of the wave. It is the safest type of wave and the best for body surfing.

This is an example of a spilling wave.

Surging waves never actually break as they approach the water's edge. They can be dangerous to small children as they are hard to notice.

This is an example of a surging wave.

Waves usually travel in groups of between two and four called a set. The break between sets is called a lull. Waves in a set also differ in size with:

the first wave being the smallest
the second wave being of medium size; and
the third wave being the largest.

wave conditions
This image shows a set of waves.

Currents

Waves push water towards the beach and as the beach slopes upwards, the water returns to its original level. The water then moves out to sea forming currents in areas along the coastline. The most common current is a rip which is responsible for more than 89% of rescues and drownings that occur around Australia. A rip is typically associated with water moving out to sea constantly.

Click on the arrow to show the water movement in a rip.

How do I identify a rip?

A rip has the following characteristics:

A darker colour, indicating deeper water.
Murky brown water caused by sand stirred up off the bottom.
Smoother surface with much smaller waves, next to white water (broken waves).
Waves breaking further out to sea on both sides of the rip.
Debris floating out to sea.
A rippled look, when the water around is generally calm.

What if I'm caught in a rip?

If you are caught in a rip remember to:

Stay calm.
Do not try to swim against the current.
Escape the current by swimming in a direction parallel to shore. When free of the current, swim at an angle - away from the current - toward shore.
If you are unable to escape by swimming, float or tread water. When the current weakens, swim at an angle - away from the current - toward shore.
If at any time you feel you are unable to reach shore, draw attention to yourself; face the shore, call or wave for help.

Important:
The larger the waves, the more intense the rip will be. Why? The more water that is being pushed towards the beach, the more water that has to return out to sea.

Ocean conditions are constantly changing. This includes the depth of water you may be in when waves travel past you, sometimes lifting you from the ocean floor. Many rescues occur because of this normal action of the ocean. When a wave comes through, even if it isn't breaking, it can lift you off the sand. This, combined with water moving back out to sea, results in people struggling with the depth of water and needing to be rescued.