The Lac Mégantic marsh is the largest wetland in the south of the St. Lawrence River due to its position and the basin-shaped valley. The path of the prevailing winds favors the accumulation of clouds that release precipitation at the head of the lake and in the Woburn Valley. Close to the water flow line that originates from the Appalachian Mountains, the marsh is continuously fed. These are the perfect conditions for a diversified flora and fauna.
Popular for hunting and fishing, the marsh is home to a diverse fauna. You can meet, among others, ducks, bustards, moose, roe deer, otters, beavers, muskrats, frogs, kingfishers, owls, herons, geese and all kinds of fishes and birds.
In the section of the marsh on the side of the municipality of Frontenac, there is also an archaeological site, the Méganticois. There are traces of the first Paleo-Indians who passed there about 12,500 years ago.