Model experiments were conducted in the circulation tank and the wave tank in order to investigate the shapes of concrete structures with an air layer to be installed into the opening of fishing ports water area for confining and cultivating sea cucumbers, taking advantage of the property that the air layer inhibits the behavior of creeping aquatic animals. As a result of the experiment in the oscillating water tank, it was found that the models of the longer the basal plate, the shorter the top edge, the lower the both side edges were the less sand accumulation just below the air layer. While, the result of the experiment in the wave tank showed that the sand accumulated just below the air layer of the model originated from the sand scoured contact with the edge of the model. In addition, a negative correlation was found between the amount of sand accumulated below the air layer and the amount of air leaked from the air layer. If the air layer is lost, the ability to confine and cultivate sea cucumbers in the fishing port waters will be lost. Based on these results, the concrete structure with a width of 3 m, a depth of 1.84 m, and a height of 0.6 m was designed based on the model of the shape with the least amount of sand accumulation just below the air layer, and would be used for the demonstration test.
