Water enters through a subsurface opening into a chamber with air trapped above it. The wave action causes the captured water column to move up and down like a piston to force the air through an opening connected to a turbine.

An oscillating water column device harnesses the motion of ocean waves as they pressurize a pocket of trapped air. This device is a partially submerged chamber with air trapped above the water surface. As waves enter and exit the chamber, the water surface moves up and down and acts like a piston. This generates electricity. The air trapped above the water level is compressed and decompressed by this movement to generate an alternating stream of high-velocity air through an exit blow hole. This air is channeled through a turbine-generator to produce electricity. These devices may be fixed to the ocean floor, hang from a floating or shoreline structure, or built into harbor jetties.

The Oscillating Water column is one of the most investigated and frequently installed technologies to date.

Illustration: As waves enter and exit the chamber, the water surface moves up and down and acts like a piston. This generates electricity.

Examples of the oscillating water column are Oceanlinx and Wavegen.