There are nineteen major shipwrecks in the 276 square miles of the Thumb Area Bottomland Preserve in lower Lake Huron. Divers can expect to find shipwrecks in a variety of conditions, from intact to very broken up. Visibility in this region is often excellent, with up to 50 feet not uncommon. This Preserve contains many shipwrecks that have yet to be located. When diving in this area, look for debris trails that could lead to important and exciting discoveries.