A sea wall is a structure built along the shoreline of an ocean, lake, or river to protect against erosion and flooding. It is also known as a BLOCKADE or DIKE. Sea walls are typically made of concrete, stone, or other materials that are strong enough to withstand the force of the water. They can also be used to create artificial harbors or breakwaters. Sea walls are an important part of coastal defense and can help to reduce the risk of flooding and erosion.