The Physics of the Perfect Dive

There's a tumblr dedicated to "celebrating the fluid dynamics of sport." From the entry on diving:

Divers twist and spin gracefully in the air, but the highest marks come when they enter the water with little to no splash. This rip entry—named after paper-ripping sound characteristic of such a dive—is possible thanks to fluid dynamics. Any time a solid object enters a still liquid, it tears a cavity into the liquid. The smaller this cavity is, the less the liquid will rebound and splash when the cavity gets refilled. In diving, achieving a small splash requires a couple items. First, the diver will grab his hands over his head to form a flat surface. This will create the initial small cavity through which his body follows. When entering, the diver will keep his body straight and rigid, with arms pressed against his head; this adds stability to keep the diver from letting the force of striking the water at 35 mph affect his body’s form and create splash. Finally, the perfect dive enters vertical to the water surface. This ensures that all of the diver’s body finds its way into that cavity created by the hands without striking any undisturbed water. Once under the water, divers often extend their arms to generate enough drag to slow down quickly. All in all, the rip entry minimizes the cavity size and thus the splash, adding a great exclamation point to a beautiful dive.

(Image: "Tom Daley of Great Britain competes in the Men's 10m Platform Diving Final on Day 15 of the London 2012 Olympic Games." Al Bello / Getty)