Very nice.
I like underwater settings and even in this early stage I thought it was atmospheric, the music helped a lot.
The jumping controls fine, the throwing less so, I had to basically look at the ceiling to hit distant targets like the first blue patch.
You can drop an harpoon while aiming and the character will stay in the throwing pose
Also she says the zipline mechanics wasn't clamplicated but the buggy part is that as you prepare the second throw the first harpoon pulls you to it and then when you press Q to merge the two tethers into a zipline the character lets go of the tether and falls down.
I hope you keep working on this, it's interesting.