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Rip currents, undertows, and ocean water survival

Emergency numbers differ by country. This page uses 911, the number for the United States and Canada. Many other countries use 112, 999, or another number. Find the number for your country.

Rip currents account for more than 80 percent of rescues performed by surf lifeguards worldwide and claim hundreds of lives every year along the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, and the Gulf of Mexico. A rip current is a powerful, narrow channel of water flowing away from the beach out through the breaking surf at speeds up to 2.4 meters per second (8 feet per second), faster than an Olympic swimmer can sprint. Knowing how to recognize a rip current from the sand, how to float and swim parallel to the shoreline rather than fighting the water, and how to help a struggling swimmer without becoming a second victim will save your life at the beach.

Do this now

If you suddenly feel yourself being pulled away from the beach into deeper water by a rip current:

  1. Stay calm and do not fight the current: Panic and exhaustion are what cause drowning in a rip current. A rip current will not pull you underwater; it only carries you on the surface away from the shore.
  2. Stop swimming straight back toward the beach: Even the strongest swimmer cannot swim directly against a fast rip current. Trying to sprint straight to shore against the flow rapidly drains your muscles and leads to drowning.
  3. Float or tread water to conserve your energy: If the current is strong, relax your body, roll onto your back to float, or tread water gently. Let the current carry you past the line of breaking waves where the outward flow naturally weakens and spreads out (usually 30 to 100 meters / 100 to 300 feet offshore).
  4. Swim parallel to the shoreline: Once you have caught your breath, swim parallel to the beach (following the shoreline to the left or right). Most rip currents are only 6 to 30 meters (20 to 100 feet) wide, so swimming parallel for a short distance takes you completely out of the seaward channel.
  5. Angle back to shore through the breaking whitewater waves: Once you are out of the narrow current channel, turn and swim diagonally back toward the beach, letting the whitewater surf push you toward the sand.
  6. Signal for help if you cannot escape: If you are too tired to swim parallel to shore, stay on your back to float, face the beach, wave one arm high over your head, and shout for help to alert lifeguards or bystanders.
flowchart TD
    Caught["Caught in a Rip Current: Pulled Seaward Away from Beach"] --> Calm["1. Stay Calm: Rip Currents Pull You Out, Never Underwater"]
    Calm --> Stop["2. Stop Swimming Straight Against the Current Toward Shore"]
    Stop --> CanSwim{"3. Do You Have Energy to Swim Sideways?"}
    CanSwim -->|Yes| Parallel["4. Swim Parallel to the Beach Until Out of the Narrow Channel"]
    CanSwim -->|No: Exhausted| Float["4. Float on Your Back, Wave One Arm, and Shout for Help"]
    Parallel --> Return["5. Swim Diagonally Back to Shore Where Whitewater Waves Break"]
    Float --> RideOut["Let Current Carry You Past Breakers Where It Weakens, Then Swim Parallel"]
    RideOut --> Return

Rip currents vs undertows vs longshore currents

Beachgoers frequently confuse the terms "rip current," "undertow," and "rip tide." Understanding the physical differences between these ocean movements prevents dangerous mistakes in the water.

Ocean Water Movement Direction of Flow How It Works What It Does to a Swimmer Survival Technique
Rip Current (often miscalled a "rip tide") Horizontal and seaward (perpendicular away from the beach) Breaking waves push water over an offshore sandbar; the trapped water funnels back out to sea through a narrow gap or trench in the sandbar Carries the swimmer rapidly out past the breaking waves on the surface; never pulls you down to the bottom Float to conserve energy; swim parallel to the shoreline until clear of the narrow channel, then angle back to the beach
Undertow (Wave Backwash) Downward and slightly seaward only in the immediate shore-break zone When a steep wave crashes directly onto a steeply sloped beach, gravity pulls that sheet of water back down the slope underneath the next incoming wave Can knock your feet out from under you in waist-deep water and pull you for 2 to 3 seconds into the base of the next breaking wave Stay calm, hold your breath for a few seconds until the wave passes, push off the sandy bottom, and walk out between waves
Longshore Current (Littoral Drift) Parallel to the shoreline (along the beach from left to right or right to left) Waves hitting the coast at an angle generate a steady river-like flow moving sideways inside the surf zone Gradually drifts swimmers down the beach away from their towels, lifeguards, or into jetties and piers Swim toward shore at an angle with the drift, or walk back up the dry sand to your starting point
Tidal Current (True Rip Tide) Inward or outward through narrow coastal inlets, estuaries, bays, and harbor mouths Driven by the gravitational pull of the Moon and Sun as the ocean tide rises (flood tide) or falls (ebb tide) through a narrow bottleneck An outgoing ebb tide through an inlet or river mouth can sweep swimmers miles offshore with no easy parallel escape Never swim in coastal inlets, river mouths, or harbor channels; float and signal for boat or lifeguard rescue immediately

How to spot a rip current from the beach before entering the water

Before setting foot in the ocean along the Atlantic, Pacific, or Gulf of Mexico coasts, spend two minutes standing on the dry sand or an elevated dune watching the wave patterns. Look for these five classic visual clues that reveal a rip current channel:

  1. A deceitfully calm gap in the breaking waves: As swells roll in toward the beach, whitewater waves break over shallow sandbars. A rip current carves a deeper trench through the sandbar where waves do not break, creating a narrow patch of flat, darker water sandwiched between breaking whitewater waves on both sides. Inexperienced swimmers often walk straight into this calm-looking gap, not realizing it is a fast-moving conveyor belt heading out to sea.
  2. A channel of churning, choppy water: The surface of a rip current often looks rippled, bumpy, or crisscrossed compared to the smoother water on either side, like a river flowing backward into the ocean.
  3. A plume of discolored, sandy, or foamy water: Because the outgoing current scours the sea floor, it carries a visible cloud of tan sand, silt, seaweed, or surface sea foam out past the line of breaking waves (forming the "head" of the rip current, shaped like a mushroom cloud).
  4. A noticeable break in the incoming wave pattern: Even when small waves cross the rip channel, the outward flow slows them down so they do not line up evenly with the waves on the left and right.
  5. Permanent structures entering the water: Rip currents almost always form directly alongside rock groins, stone jetties, concrete piers, and outfall pipes, which deflect longshore currents straight out to sea. Never swim within 45 meters (150 feet) of any pier or jetty.

Wear polarized sunglasses to spot rip currents

Polarized sunglasses cut the blinding glare off the ocean's surface and make it much easier to see the contrast between shallow tan sandbars (where waves break safely) and deep dark-blue or muddy brown trenches where rip currents flow seaward.

Understanding the anatomy of a rip current

According to the United States Lifesaving Association (USLA), the National Oceanic and Atmospheric Administration (NOAA in the United States), and Surf Life Saving Australia, every classic rip current consists of three distinct parts:

  • The Feeder Currents: Moving parallel to the shoreline inside the shallow surf zone, feeder currents collect the water piled up on the beach by breaking waves and carry it sideways toward the lowest gap in the sandbar.
  • The Neck: This is the narrow, fast-moving channel (typically 6 to 30 meters / 20 to 100 feet wide) where the feeder currents converge and rush straight out through the surf zone at speeds between 0.5 and 2.4 meters per second (1.6 to 8 feet per second). The neck is where swimmers feel pulled away from shore.
  • The Head: Just beyond the line of breaking waves (usually 30 to 100 meters / 100 to 300 feet from the beach), the deep trench ends. The outgoing water hits the deeper ocean, spreads out into a fan or mushroom shape, and slows down to a stop.

Because a rip current does not continue miles out into the open ocean, floating on your back through the "neck" until you reach the calm "head" outside the breakers is a proven survival method when swimming sideways inside the neck feels too difficult. Note that some rip currents circulate in a closed loop, meaning if you swim back in at the wrong spot you can be drawn back into the feeder current; always aim for the areas where whitewater waves are actively breaking over shallow sandbars, as breaking whitewater pushes you toward the beach.

Safe bystander rescue: "Throw, Don't Go"

One of the most tragic and common occurrences in ocean emergencies is the death of a good Samaritan. Every year, parents, friends, and bystanders jump into the surf without a flotation device to save someone caught in a rip current, only for the panicked victim to climb onto the rescuer, drowning the rescuer while the original victim survives or both drown.

Never enter the ocean to rescue someone without a flotation device

A panicked, drowning adult possesses overwhelming reflexive grip strength and will instinctively push a swimmer underwater to keep their own head above the surface. Unless you are a trained surf lifeguard carrying a rescue tube or surfboard, never swim out to a drowning person empty-handed. Follow the international water rescue rule: Reach, Throw, Row, Don't Go.

If you see someone struggling in a rip current or calling for help from the water, follow these steps in order:

  1. Alert a lifeguard or call emergency services first: Wave down the nearest beach lifeguard immediately. If the beach is unguarded, call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom, or see our emergency numbers guide) and keep your eyes fixed on the swimmer's exact position relative to a landmark on shore.
  2. Shout clear instructions from the beach: Run to the water's edge, cup your hands around your mouth, and yell: "Float on your back. Stop fighting the current. Swim parallel to the beach." Point horizontally down the shoreline in the direction they should swim (away from piers and toward breaking waves).
  3. Throw anything that floats: Look around the beach immediately for any buoyant object you can throw or push to the victim, or that a strong swimmer with fins/surfboard can push in front of them as a barrier:
  4. A surfboard, bodyboard (boogie board), or stand-up paddleboard (the single best rescue tools on any beach).
  5. A coast guard ring buoy, rescue tube, or life jacket (PFD).
  6. An emptied plastic picnic cooler with the lid latched shut (an empty cooler holds an adult effortlessly above water).
  7. An inflated beach ball, pool float, or sealed empty 4-liter (1-gallon) water jug.
  8. Keep a flotation barrier between you and the victim: If you are an experienced ocean swimmer with a surfboard or bodyboard and must go out because no lifeguards are present, never let the panicked swimmer grab your body or neck. Stop 2 meters (6 feet) away, push the nose of the surfboard or cooler into their hands, tell them to hold onto the board, and kick them parallel to the beach out of the current.
  9. Provide post-rescue care on shore: Once the person is back on dry sand, check their breathing immediately. Even if a rescued swimmer is conscious, anyone who inhaled even a small amount of saltwater and is coughing persistently, wheezing, or confused must go to a hospital emergency department to be monitored for secondary lung injury (see our drowning first aid guide).

Beach warning flags and proactive ocean safety

Most lifeguarded beaches in the United States, Europe, Australia, and Latin America use the standardized International Life Saving Federation (ILS) color-coded beach warning flags:

  • Double Red Flags: Water is closed to the public; entering the water is extremely dangerous and often illegal.
  • Single Red Flag: High hazard; high surf and/or strong rip currents. Only experienced ocean swimmers with flotation gear should enter, and only near a lifeguard.
  • Yellow Flag: Medium hazard; moderate surf and/or currents. Weak swimmers and children should wear Coast Guard-approved life jackets and stay waist-deep near lifeguards.
  • Green Flag: Low hazard; calm conditions, though rip currents can still form unexpectedly near sandbars and piers.
  • Purple Flag: Dangerous marine life present (such as jellyfish, Portuguese man-of-war, or stingrays; see our jellyfish stings first aid guide).
  • Red and Yellow Halved Flags: Lifeguarded bathing zone; always swim between the red-and-yellow flags where lifeguards are actively watching.

Frequently asked questions

Will a rip current pull you underwater to the bottom of the ocean?

No, a rip current is a surface current that flows horizontally away from the beach toward the open ocean; it never pulls swimmers underwater, though panic and exhaustion from trying to swim straight against it can cause a swimmer to go under.

What is the difference between a rip current and an undertow?

A rip current is a narrow channel of water flowing horizontally out past the breaking waves, whereas an undertow is simply the brief downward backwash of a crashing wave sliding down a steep beach slope underneath the next incoming wave.

Why shouldn't you swim straight back to the beach when caught in a rip current?

Rip currents flow seaward at speeds of 0.5 to 2.4 meters per second (1.6 to 8 feet per second), which is faster than even an Olympic swimmer can swim, so swimming directly against the current quickly exhausts your muscles without making forward progress.

How can you rescue someone in a rip current without drowning yourself?

Call emergency services or alert a lifeguard first, yell instructions to float and swim parallel to the shore, and only assist by throwing or pushing a buoyant object like a surfboard, bodyboard, life ring, or empty latched picnic cooler so the panicked swimmer cannot pull you underwater.