It's just water, what we've seen in the caverns can't be all that different from what's here in the lake!

[Managing to free one foot from the mud and stepping back on to slightly dryer land, Noct works to get his other leg free as he struggles - there's a yank on the line that almost makes him take that step back, but Hank holding him steady even through his jacket prevents a full step. Grunting, struggling back that next step and giving a little relieved exhale, it's short lived as Noct tries to pull back with his pole again.

It's giving, little by little. Whatever is on the end is getting tired enough to come out of the depths at last.]

I'd struggle until my line broke, probably. Or I'd go for a swim. Usually Gladio is around to help me haul catches like this. Once I get it to the surface, he steps in to muscle it to shore.