A cofferdam is a temporary structure used to create a dry work environment in areas that are usually submerged in water. It is typically made of steel, wood, or concrete and is built around a construction site, allowing workers to safely perform tasks such as building foundations or repairing bridges. Cofferdams are commonly used in projects involving rivers, lakes, or coastal areas. Once the area is dewatered, construction can proceed without the complications of water interference. After the project is completed, the cofferdam is removed, and the water is allowed to flow back into the area.