[glurgh]

In a 300 foot fall, you're not reaching the bottom at terminal velocity. Mythbusters have in fact gone over this a few times and the results are a bit different - falling from such a height onto more or less anything is almost certainly lethal. Given equivalent height, even at terminal velocity, you're still slightly better off falling into water.

[base698]

You're still going about 80 mph. Just from memory it's roughly 20 mph/second until you hit 4 seconds where it's reduced to 10 mph/second due to air resistance. The greatest chance you'd have is to impact shallow water with mud. This has saved at least three people, of which there are fairly spectacular Youtube videos.