The Water Sprint skill feat is here:
https://2e.aonprd.com/Feats.aspx?ID=6515
"Experience and training have taught you that water has just enough surface tension for a master sprinter to traverse the surface. When you Stride in a straight line, if you move at least half your Speed over ground, you can move any amount of the remaining distance across a level body of water. If you don't end your Stride on solid ground, you fall into the water.
If you're legendary in Athletics, as long as you start on solid ground, any part of your Stride can cross the water's surface, even if you aren't moving a straight line, though you still fall into the water if you don't end your movement on solid ground."
Leap is this:
"Leap
The Leap basic action is used for High Jump and Long Jump. A horizontal Leap lets you jump up to 10 feet horizontally if your Speed is at least 15 feet, or up to 15 feet horizontally if your Speed is at least 30 feet. You land in the space where your Leap ends (meaning you can typically clear a 5-foot gap if your Speed is between 15 feet and 30 feet, or a 10-foot gap if your Speed is 30 feet or more)."
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The Water Sprint skill feat refers to "Stride" which is a game term, and means a single action to move up to your (land) speed.
So for a move speed of X, then Water Sprint (before legendary) requires:
X=20': 10' over ground, 5' over water, ending on 5' of solid ground.
X=25': 15' over ground, 5' over water, ending on 5' of solid ground.
X=30': 15' over ground, 10' over water, ending on 5' of solid ground.
The way it is phrased, the rules apply to each Stride Action, so you can't "Stride 3 times" to cover a wider body of water. Each individual Stride has to start with "at least half over ground" and "end on solid ground".
Compared to the basic Leap action that covers that gap, no feat needed.
Or someone of level 7 and Master in Athletics doing a 2-action Long Jump, who will cover 13+1d20 feet, with at least 10' of a Stride action beforehand.
I can see occasional situations where Water Sprint saves an action, if the destination is exactly 1 Stride away, with a water barrier of no more than 10', immediately before the destination.
Or if your land speed has been significantly boosted.
...Is it just me, or is this *really* niche?
Or perhaps I have I miss-understood how these rules apply, and it works better than this??
(Or is it a gag, they are just doing a long jump and deluding themselves?)