How to properly fall into water from great height

[Jester]

A smaller object (like a hammer, which Mythbusters used) just doesn't have enough of an effect. Whether the bubble content of the water can be made high enough to help seems iffy - and of course, if the object is too large, you end up going splat into the back of the rock instead of the water. :)

Jumping out of a plane with no parachute, it's not implausible that you might have something smallish that you could throw in front of you. It'd be pretty freaky if you had a boulder - where'd that come from? (Maybe you were making a connecting flight in Colorado? Nyuk nyuk...) If we're talking about something large enough to have the necessary effect, we're also talking about something well beyond the "unaided" free fall.

-Jester