Hello, thank you for taking the time to play my game and leave such a detailed comment!
As for the bars & the tentacle turning black - these things are explained in the 'how to play' section of the game, which admittedly does have a bug right now but you can still read all of it if you flip forward two pages and then back to the first (this will be fixed as soon as I can edit files again, it's already fixed locally). But the tentacle turning black is an ability called 'Dive', its to avoid icebergs. You activate it with 'E' or 'U'/Shift.
Yes, a few people have suggested differentiating the tentacles more. I'll for sure work on that!
There is a powerup sound, I'll look into making a 'frozen' sound for hitting the icebergs. As for differentiating the barrels more - I was working on more art and animations when the deadline hit, I just ran out of time there. I wanted all the ships to be different sprites too, not just re-colors.
I mean, you can destroy the ships with whirlpools, but I assume you're asking if you can destroy them with just your tentacles? I feel that that might make whirlpools kind of pointless, which is supposed to be the main mechanic. Maybe I could make another powerup that lets you do that for a limited amount of time?
Thank you again for your time and comment! Have a wonderful day and good luck in the Jam!