What is a Seawall?

Mary McMahon
Mary McMahon

A seawall is a structure that is designed to protect a shoreline from flooding and erosion. They are typically only one part of a larger coastal defense system that is designed with several protections in case one or more fail. Many visitors to sea-side towns are familiar with the concept of a seawall, as are residents of these regions. There are a number of different ways to construct one, depending on available materials and the needs which it needs to meet.

Seawalls can help insulate communities from flooding.
Seawalls can help insulate communities from flooding.

Essentially, a seawall acts as a layer between the vulnerable coastline and the ocean. Wave action can beat at the wall without eroding the coast, although the structure itself will eventually break down and require repair or replacement. Seawalls also help to insulate communities from flooding, although high waves can still breach most seawalls. It can also provide a space for recreation, since the top is often flat, allowing people to walk on it or to fish from it.

During storms, waves are often strong enough to damage houses and roads.
During storms, waves are often strong enough to damage houses and roads.

In some cases, a seawall will be constructed on shore to break high waves that might otherwise damage structures and roads on the shore. In these instances, several lower barriers may precede it, to help break up the wave energy before the waves hit the wall. Other seawalls are built in the water right next to a shoreline, as is the case on many islands. Some nations also build them in the open water to act as flood barriers and to dissipate waves before they reach the shore, encouraging them to break more gently.

Many seawalls are curved, allowing waves to break against them while reducing their energy. Others are straight, and they are designed to bring waves to a standstill. It is not uncommon to bury low mounds of rubble in front of them to assist with the goal of reducing the power of waves as they hit the shore. In the case of a seawall that is meant to resist flooding, it may be quite high so that it can cope with storm surge.

Traditional seawalls are built from large rocks, pebbles, and other rubble; some remains of ancient seawalls built in this style can be seen in many communities. A modern structure can be made from these materials, although it may also integrate concrete, metal bars, and other tools to make it more sturdy. Cheaper seawalls may be made from wood and plastic, which provide some protection, although they can potentially fail in heavy weather.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I was in Galveston, Texas a month after Hurricane Ike to visit relatives and also to see how much damage the hurricane had caused in the city.

There was damage due to flood waters but nothing that couldn't be dealt with. Everyone kept telling me that they were saved thanks to the Galveston seawall. If the seawall hadn't been there, the damage would have been immense. Many lives would could have been lost and my family could have been among them.

I personally think a seawall needs to be constructed for all coastal cities. We experience some kind of a hurricane practically every year. Too many people and their properties have already suffered from these disasters. Seawalls cannot be too expensive to build and they are a great protective barrier. It's worth the investment.


I think sea walls are used to make use of ports easier right?

I live in a small town on the coast and we have a pretty short seawall and an anchorage that is attached to it. Boats can anchor in this area without getting to close to the shoreline. People also like to take strolls on its bridge on weekends and evening and some like to fish.

I like the seawall because I can be near the water without getting myself into the sand. It's very nice to exercise there too.

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