I leveled up my swimming a bunch for a while because there was an area that I knew I could get to if I swam and had enough stamina...not sure about my reasons of why I didn't at least build a small boat but I think my reasoning was that there was many rocks in the way, which also allowed me to swim there. I think also I did it because I wanted to see if I could do it.

Definitely worth leveling just so you can cross small areas of water easily...always useful in case you break a boat.

Originally posted by Nicholas Gurr, Blackpill Ph.D:

if its anything like running and jumping, you wont even notice the difference. i read somewhere that the difference between 0 running and 100 running is like 5% slower stamina depletion. a complete joke. why even have skill levels at all if they're this insignificant and you lose them on death anyway.

Not sure about this as on my highly leveled character, I jump so high and run so fast that I take a small bit of damage when I hit the ground, so I have to strafe whilst in the air. I only do this to level up jumping even further.