Jetties and Piers: Why Swimming Near Them Is Risky

Swimming near a jetty, groin or pier is risky because rip currents often form right beside these structures and stay there. The American Red Cross says to stay at least 100 feet away from piers and jetties (opens in a new tab) while you're in the water, because permanent rip currents often exist near them.

Jetties and piers are great places to look at the ocean. They are bad places to swim, and in big surf they can be dangerous to stand on too.

What these structures are

You'll see three kinds of structures on many beaches:

• Jetties. The National Weather Service (NWS) defines a jetty as a structure extending into a body of water to direct and confine the stream or tidal flow to a selected channel (opens in a new tab), usually at the mouth of a river or the entrance to a bay.
• Groins. The NWS describes a groin as a shore-protection structure (opens in a new tab), often built to trap sand or slow erosion. Groins are narrow and stick straight out from the beach, sometimes for hundreds of yards.
• Piers. Built for walking and fishing, on pilings that stand in the surf.

All three change how waves break and how water moves near them.

Structures and rip currents

The NWS says rip currents often occur adjacent to man-made structures such as groins, jetties, and piers (opens in a new tab), as well as natural features like headlands and rocky outcrops. It calls these "structural" rip currents and says they:

• Stay put. They are persistent in location (opens in a new tab). They have also been called "permanent" rip currents.
• Form in small waves. They can occur even during small breaking wave conditions (opens in a new tab).
• Can be stronger. The NWS Tallahassee office says rip currents commonly form near inlets, jetties and piers, where they are more intense (opens in a new tab).

Why it happens

The NWS explains two ways structures make rip currents:

1. Deflection. Waves usually hit the beach at an angle and push a current along the shore. When that current encounters coastal structure (such as a groin, jetty, or pier) it is deflected in an offshore direction (opens in a new tab). That offshore flow is a rip current.
2. Shadow. On the sheltered side of a structure, waves are smaller. Water flows along the shore toward the calmer area, then turns out to sea alongside the structure.

These rip currents can form on both sides of the same structure at once.

Even on "low risk" days

Rip current forecasts include a warning just for structures. The NWS says that even when the risk is low, life threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers (opens in a new tab). So a calm day is not a reason to swim next to the rocks.

NYC Parks gives the same warning for city beaches: rip currents occur most often at low spots or breaks in the sandbar and in the vicinity of structures such as groins, jetties and piers (opens in a new tab).

The water near the rocks

Apart from rip currents, the water around structures has other hazards:

• Deeper water. The NWS says structural rip currents are sometimes associated with deeper water adjacent to structures (opens in a new tab), which can look darker and calmer than the water around it.
• Rocks, pilings and debris. Underwater rocks and old pilings are hard to see. CDC notes that natural water hides hazards such as dangerous currents or waves, rocks or vegetation, and limited visibility (opens in a new tab).
• Inlets and tidal currents. Jetties often line inlets. The NWS says strong currents often occur in tidal inlets, mouths of estuaries and harbor openings (opens in a new tab), with both incoming and outgoing tides. Don't swim in or near an inlet.

Fishing and walking on jetties

Many people walk out on jetties to fish, explore or take photos. That's when the risk changes from currents to waves and weather.

• High surf washes over them. The NWS says high surf has enough energy to wash over jetties or exposed rocks (opens in a new tab).
• Falls lead to cold water. The NWS lists falling off watercraft, docks, rocks or jetties (opens in a new tab) as one way people end up suddenly in cold water, which can trigger gasping and drowning.
• Lightning. The NWS says fishing is the leading cause of lightning fatalities (opens in a new tab), with fishermen on piers, large rocks and sandy beaches as well as in boats.

If you fish or walk on a jetty or pier:

• Check the surf and weather forecast before you go.
• Stay off the rocks when waves are washing over them, or if they are wet and slippery.
• Never turn your back on the ocean.
• Wear a life jacket on jetties, and bring something you can throw to someone who falls in.
• Leave at the first sound of thunder. The NWS says to head to a vehicle or a large, fully enclosed building, not an open-sided shelter.
• Follow posted signs and closures.

Our fishing safety guide covers life jackets, cold water and weather for anglers.

Where to swim instead

• Swim in the middle of the lifeguarded area, away from the ends where structures are.
• Follow the lifeguard's directions. They know where today's rip currents are. See why swimming near a lifeguard matters.
• Surfers and bodyboarders: stay away from the rocks too. NYC's Rockaway surf rules say plainly: stay away from the jetty (opens in a new tab).
• At NYC beaches, closed sections are marked with signs and/or red flags (opens in a new tab). Never swim in them. See NYC beach safety.

If you do get caught in a rip current next to a structure, the escape is the same: relax, float, and swim parallel to shore, away from the structure, before angling back. Learn the steps in how to escape a rip current.

What you can do today

1. Make "100 feet from the rocks" a family rule. That's a little longer than a basketball court.
2. Look at a map of your beach before you go, and note where the jetties, groins and piers are.
3. Check the surf forecast before any walk or fishing trip on a jetty.
4. Pack a life jacket for anglers in your family, and read our fishing safety guide.
5. Read up on shore break and big waves, the other hazard near rocks and steep beaches.