Engineering students from around the world gathered at Evergreen Lake on Monday to race canoes built out of concrete.
The group apparently needed a challenge.
The National Concrete Canoe Competition is hosted by the Colorado School of Mines.
PHOTOS: Concrete canoe races
The 205 teams of civil engineering students have one year to develop and build the canoes.
Students must use a special mix of concrete, which is less dense than water.
They weigh, measure and judge the look of the canoes over the weekend. Then on Monday, all of the teams travel up to the lake in Evergreen to race them and make sure they actually do float.
Winners are determined in the races as well as design and presentation.
The races run at Evergreen Lake until 3:30 p.m. Monday.