Another interesting, if slightly more frivolous, use of hydrodynamics is in swimming.
Throughout the years, swimming has progressed from basic thrashing to prevent drowning to the elegant and highly technical sport it is today. A major reason behind the changes in technique that have come about in the past several years is the studied application of hydrodynamics to swimming.
Coaches and swimmers alike not only focus on strength, but also on where and how to apply pressure and force to the water in order to maximize speed and minimize water resistance to the swimmer's body.
As a former swimmer, I could go on forever about this, but I would be curious to know if there are similar unusual fields that have benefited from the application of hydrodynamics?