... or in this case, creative, they design things like this: http://www.eta-hpb.de/
Stefan Riederer is one of BMW's engineers (and a heck of a nice guy), and in talking with him over dinner during the launch of the new (and impressive) ActiveHybrid 7, he mentioned that he designed and built the unusual bicycle-based hydrofoil seen in action below.
Completely human powered, it doesn't float at all, relying entirely on forward motion and hydrodynamics to keep it from sinking. Stefan used to work in BMW's aerodynamics lab, which no doubt helped in this pursuit.
What would he like to tackle next, were space and expense not major considerations? Human powered flight. Doubtless this man could do it...
(Photo courtesy of Stefan's website, found at the above link)