A seawall is a strong wall built along a coastline to protect the land behind it from ocean waves and flooding. These massive barriers, usually made of concrete, stone, or steel, act like shields between the ocean and everything people have built near the shore: houses, roads, businesses, and farmland.

Seawalls work by blocking or deflecting the force of crashing waves, especially during storms when the ocean becomes violent and destructive. Without seawalls, powerful waves would erode beaches, wash away soil, and flood coastal communities. Cities like Miami and Galveston have built extensive seawall systems to protect themselves from hurricanes and rising tides.

Building a seawall is anything but simple. Engineers must design them to withstand millions of tons of water pressure over decades. Some seawalls stand twenty feet tall or higher.

While seawalls protect property and lives, they can create problems too. They sometimes cause beaches to shrink by disrupting the natural flow of sand, and they can block access to the water. Coastal engineers constantly work to design seawalls that protect communities while minimizing harm to beaches and ocean habitats. In places where the ocean is rising or storms are becoming stronger, communities must decide whether to build new seawalls, strengthen old ones, or relocate inland.