This takes a few seconds of watching to get oriented, but what you are looking at are outflow draft tubes from a hydroelectric dam in the state of Washington. The 3D data was collected in just 4 hours at a depth of 65 feet using BlueView Technologies 3D multibeam underwater scanning technology. The scanner is mounted on a tripod and placed on the bottom.
The consultant, Tetra Tech selected the technology because they needed to be able to inspect the inside surface of the tubes as well as the outflow control doors. Traditional side scan sonar could not see inside the tubes. The data is compatible with Leicas Cyclone software.
This is a powerful technology to have in your toolbox.