Lac Seul is a crescent shaped reservoir approximately 150 miles long, first flooded in 1935. It is the second largest body of water entirely within the province of Ontario. The lake consists of open water, bays, natural channels and islands. It is a relatively shallow lake with many rocky shoals. This provides good habitat for walleye and northern pike. Lac Seul is noted for the remote wilderness character it offers as well as some of the best fishing in Ontario. Other fish species found in Lac Seul are muskie, yellow perch, whitefish and the occasional bass.

Lac Seul is located on the former lake bed of glacial Lake Agassiz. Due to this previous lake, much of the bottom of the lake is covered with thick deposits of lacustrine silts and varved clay of varying thickness. The water of Lac Seul is tea colored. Because of the color of its water, it provides excellent walleye and northern pike angling throughout the day. Lac Seul offers some of the finest of trophy northern pike and walleye fishing as well as 50-inch muskie. It also provides the feeling of the vast, practically untouched wilderness to all who visit.