Glory Holes
Near Nova Scotia, a DIDSON works in a glory hole - a hole 9 m deep and 25 m by 50 m in size. Equipment is placed in the bottom of glory holes to protect it from icebergs which scour the bottom. A glory hole wall periodically caves and makes the water zero vis and the video screens blank. The lens-based sonar provides a sufficient vision feedback to allow work to continue during these turbid periods.
Courtesy of Oceaneering