MADISON (WKOW) -- Archaeologists have made an incredible discovery in Lake Mendota. Wisconsin Historical Society maritime archaeologists discovered a historic dugout canoe under about 30 feet of water earlier this year. They excavated it on Tuesday. Archaeologist say the canoe is remarkably intact given its age, which carbon dating has placed at 1,200 years. That means the canoe was used around 800 A.D., an era that aligns with effigy mound building in Southern Wisconsin.