A common misconception with seawalls is that their purpose is to hold back water from the property. In reality, their purpose is to hold back and retain the property from deterioration from the water.

Twin Lakes Enterprises uses almost exclusively steel sheet piles when driving sea wall supported by dead men driven to bedrock every 5 feet behind the wall. Your seawall should also be able to equalize hydrostatic pressure between water  behind the wall and in front of it – if this is not taken into consideration then fluctuations in the water level will result in a failed wall.