START SMALL
The highest Olympic-level dive distance is ten meters (33 feet), with good reason. Beware of injury at around 15 to 20 feet and know what you're doing above 30 feet. Anything over 50 is pro territory. Be conservative when guesstimating height. And never, ever dive alone. OK, there's your scary warning.

SCOUT IT
Gently toss a rock off the top to get a rough idea of where you'll land. Then walk down and pre-swim the surface—roughly a ten-foot radius—looking for branches, rocks, and any other hazards. Now do the same down to about 15 feet. Make sure it's that deep everywhere, in case you misjudge your trajectory.

DIVE OR JUMP?
Don't let anyone tell you it's safer to go headfirst. If you're at all concerned about the impact, or overrotating, go feet first.

JUMP BAREFOOT
Especially above 25 feet. Wearing shoes or sandals takes away some of the sting, but it also increases your surface area, which magnifies the force of impact and the stress on your knees, groin, and back. Use floating sandals for scrambling, then toss them down and off to the side before jumping.

BE CONFIDENT
If the wall is nearly vertical—the safest type—you don't need a running start. Imagine you're jumping off a couch and over a coffee table in one strong, fluid motion.

STAY LOOSE
Don't tense up in the air. Keep your body still and slightly relaxed. If you jump feet first and over-rotate significantly, your best bet is to enter the water in the "suicide" position (bent over as much as possible, with arms and legs pointing straight down).

NAIL THE LANDING
Feet first: Squeeze your feet together, with the balls of your feet down and toes up (like you're wearing high heels). Guys, cover the jewels. Headfirst: You want to be in a hollow position—stomach sucked in, abs and quads tensed, shoulders rolled forward. With your hands side by side, in two fists, pretend you're punching a bug on the water's surface. Diving or jumping, the most important thing is to hit the water with maximum strength—explosively, with your entire body tensed up.
—AS TOLD TO SAM MOULTON