Rip current
A strong, narrow current flowing seaward through breaking waves.
A rip current is a strong, localized, and narrow current of water that moves directly away from the shore, cutting through the lines of breaking waves like a river flowing out to sea. It forms when wind and breaking waves push surface water toward the land, causing a slight rise in water level along the shore; the excess water then flows back to open water via the route of least resistance, often through a gap in a sandbar or reef.
- type
- Water current
- occurrence
- Coasts of oceans, seas, and large lakes with sufficient wave energy
- characteristics
- Strong, localized, narrow; strongest near the surface; flows away from shore
- misconception
- Not the same as undertow; cannot pull a person down and hold them underwater
Lore & Background
A rip current forms because wind and breaking waves push surface water towards the land, causing a slight rise in water level along the shore. This excess water tends to flow back to open water via the route of least resistance. When there is a local area which is slightly deeper, such as a break in an offshore sand bar or reef, this can allow water to flow offshore more easily, initiating a rip current through that gap. Water pushed up near the beach flows along the shore towards the outgoing rip as 'feeder currents,' then flows out at a right angle to the beach in a tight current called the 'neck,' where the flow is most rapid. When the water reaches outside the lines of breaking waves, the flow disperses sideways, loses power, and dissipates in what is known as the 'head' of the rip.
Reader's Guide
Rip currents are significant because they are a leading cause of drowning and rescues at beaches worldwide, yet they are often misunderstood. Contrary to popular belief, a rip current cannot pull a person down and hold them under the water; it simply carries floating objects, including people, out to just beyond the zone of breaking waves, where the current dissipates. Swimmers who panic or exhaust themselves by trying to swim directly against the flow are at greatest risk. Visually, rip currents can be identified from shore by a noticeable break in the pattern of waves, a river of foam, or a different color of water. Lifeguards watch for rip currents and move safety flags accordingly. Understanding rip currents is essential for beach safety, as studies show the majority of people are unable to identify them and therefore unable to identify safe places to swim.
Did You Know?
- Rip currents are strongest and fastest next to the surface of the water, not below it.
- A rip current can appear as a relatively smooth area of water without breaking waves, which may mislead beach-goers into entering it.
- Rip currents can form by the coasts of oceans, seas, and large lakes whenever there are waves of sufficient energy.
- In parts of the world with a big tidal range, rip currents may only occur at certain stages of the tide.
More in Coastal & Marine Geology 1-21
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