Riptide
Sources: Surf Today , Wikipedia and Weather.gov
Rip currents, riptides, and undertows are all the same thing. While the word undertow suggests going underwater, these currents will not pull you under the water per se, they'll just knock you off your feet and pull you out to sea.
Rip currents are strong offshore flows and often occur when breaking waves push water up the beach face. This piled-up water must escape back out to the sea as water seeks its own level. Typically, the return flow (backwash) is relatively uniform along the beach, so rip currents aren't present.
A rip current can form if there's an area where the water can flow back out to the ocean easily - for instance, a break in the sand bar and also near structures such as jetties and piers.
Rip currents are generally only tens of feet in width, but there may be several at a given time spaced widely along the shore. Moving at speeds of up to eight feet per second, rip currents can move faster than an Olympic swimmer. Rip currents are often detected in about knee-to-waist high water. They can be difficult to escape by walking back toward shore against the current once you are in chest-deep water. These strong, offshore-directed currents pull the water or someone at all water depths through the surf zone. The current only dissipates offshore of the breaking waves where the water can be quite deep - certainly over your head.
If you're standing at least knee-deep in the ocean then you're in enough water to be dragged out to sea by a rip current. Should you ever find yourself caught in one, follow these simple steps to escape!
- Don't fight the current! (If you try to out-swim it, you'll just wear yourself out and increase your chance of drowning. This is how most rip current deaths occur!)
- Swim parallel to the shoreline. Keep doing so until you no longer feel the current's pull.
- Once free, swim back to land at an angle.
If you "freeze up" or feel unable to do the above, then stay calm, face the shore and loudly call and wave for help. The National Weather Service sums up these survival nicely with the phrase, wave and yell...swim parallel.
Rip currents can occur at any time and on any day, regardless of the tidal cycle. Rip currents tend to be stronger during low tides, when the ocean water level is lower. Tides are not present in the Great Lakes.
Rip currents are not the only way that water brought toward the shoreline by breaking waves is returned seaward. Offshore movement of water located close to the bottom also moves water out. This phenomenon is known as undertow or a near bed return flow. The term undertow has sometimes been used mistakenly to refer to rip currents and has contributed to the myth that rip currents can pull a person under the water. Undertow and rip currents are separate phenomena and neither will pull a person under the water! Undertow is usually slower than rip currents and typically does not present a hazard to swimmers.
Undertow also is often confused with the backwash of broken waves at the shoreline. After a wave breaks and runs up the beach face, the returning water is called backwash and can be quite strong, particularly on steep beaches and in the embayments of beach cusps. While this backwash will not carry water very far offshore, it can be strong enough to knock people over, particularly small children and the elderly, and carry them into deeper water.