This STEM cardboard boat project is intended for schools with access to a pool or lake. In the project students learn about buoyancy and apply the principles to develop a cardboard boat capable of carrying 2 people. The students work through the design cycle as they build prototypes, do research, and modify their boats. The project lasts around 7 class periods, culminating in a competition on the last day. Files include PowerPoints and handouts. The project was designed for students with a basic understanding of forces.