Wow! I think this is one of the best Twine poems I've read for how tightly you've combined the poem's language with its (watery, digital) medium. What made it so immersive for me was how the visuals of the text matched what happened to you as you were on the water, then under it, then drowned. I think combining the hyper-personal emotional experience that is depression with being out on the open sea, losing your bearings there, and succumbing to it in some form also evokes the terror and isolation of both very well. I hope you'll make more of these! I'd love to see how you use this program to write about other kinds of feelings.
Experimentation - 5; I'm wondering, was your piece inspired by any Twine poems in particular, or do you have any favorites? I think you really hit on a lot of what makes it such a cool poetry/storytelling software with this submission.
Interactivity - I gave this category a 3 because, while the reader must click through the poem to progress, their role is quite passive. I don't really feel like this poem needs more interactivity, though, especially given its subject matter. My favorite of these was when hovering over the back button made the "abyss" hyperlink appear.
Polish - Very! I think I caught one typo ("Vison narrows") and one of the sound pieces might have cut off a bit earlier than you'd intended it to towards the end (I can go back and find it for you if you like), but I seriously love how you brought the words under water, had them roll and shake like they would on deck.
Poetry - Definitely a poem, so 5!