A Quora member recently asked if there was any chance of survival if one jumped out of a plane at 30,000 feet, assuming they hit the water perfectly? According to N. Doty, a competitive diver and recreational skydiver, your chances of survival are extremely low.

Surviving a jump from a plane into water without a parachute is statistically highly unlikely, though there have been a handful of "miracle" survivals in history. When falling from a standard cruising altitude, a human reaches terminal velocity (about 120 mph or 193 km/h). At this speed, hitting water is physically similar to hitting solid concrete because water is "incompressible" and cannot move out of your way fast enough upon impact. The force of the impact would likely cause immediate fatal trauma to the internal organs, brain, and skeletal structure. If you were forced to jump, your best (albeit slim) chance of survival would involve hitting the water feet-first in a "pencil" position with your arms tight to your sides and your muscles tensed to protect your core. This minimizes the surface area of the impact. Even if you survive the initial hit, you would likely be unconscious or severely injured, making it nearly impossible to swim or stay afloat in the open ocean without immediate rescue.