I think it's supposed to be the currents throwing you around - it's a lot worse if the tide is going out or in (basically, any time except the height of day or the dead of night).

I never had to teleport to swim, though, even when it was quite the struggle. Not sure what's going on there.

At first I thought maybe the tides, but this is like insanity super-speed glitch-out. I get into water, and I'm thrown about (and even got the achievement for 'far swimming' in about a half second). Not thinking its intentional.... unless it was intended to have tides rip you out, but its gone haywire and it flings you left, right, forward, back, and pretty much around the entire island 2 in about 15 seconds.

Even trying to surface, or use the teleport tool... its a serious pain to try and get 'stuck' enough on something so you can actually get out of the bugged water.

I realize this was a necro lol ...

But yeah, the water gave me fits, because theres a secret item underwater in a spot, and even with the tide low, getting into the water and trying to get that item is a huge pain with this crazy 'super-speed-current' thing/glitch/bug.

I did manage to finally get the item... after a dozen attempts, and crazy use of the teleporter tool ugh.

Chiming in with a "me too". Entering the water on Island 2 results in extremely unpredictable warp-speed movement with the controls doing basically nothing.

Edit: Possibly related, the pushable block physics puzzles seem a bit bugged too. I'm in the temple puzzle thing just past Island 2, with the four blocks to push around to let you jump across the chasm, and pushing these blocks is *super* slow - like, full and complete multiples of 60 seconds to move them around slow.

Edit2: Possibly something's a bit bugged with physics completely. I've noticed that you can't actually stand completely still. It's very, very subtle, but even when you're standing still you're actually still moving very slightly.