Before you even think about jumping, check the water depth. You need at least eight to ten feet of clear, obstacle-free water. If you’re at a lake or river, scan for rocks, logs, or that one grumpy fish that will judge your form.
Also, don’t do this off a slippery dock unless you want your gainer to become a “faller in with extra regret.” I’ve seen sandals fly off like they had somewhere better to be. You want a solid, non-skid surface for your takeoff.