Nami: Redline is basically like a series of island connected together.
There are areas that's "Summer Island", and ther are those that are "Winter Island".
(half the line cut off, guessing) The one we're going straight for is probably a freezing "Winter Island" weather area.
The reason why I think so is because another element necessary for current to flow strongly downwards are there.
Luffy: Huh? What is this element you speak of?
Nami: There you go, butting into something for no reason... do you want to really hear about the ocean's salinity? (enbun noudo)
Luffy: ... yeah we use to play with soli-nitie when we were young....
Zoro: Yeah I've always wanted firenodes (Enbun noudo, a pun. Zoro doesn't know what it is, thinking it means fire instead of salt, so talking random crap)
Nami: alright, go away.
Luffy (chased away by Nami): Hey Zoro, where were you flown to?
Zoro: Yeah, check this out...
Usopp: What about solinity? Tell us, I want to know the ocean's mystery!
Nami: Well you're eager to learn... So anyways, the element needed for the current to flow downwards is "cold and heavy water".
In freezing areas, there are iceburgs, and when the iceburgs are formed, the solinity level....
Luffy/Zoro/Usopp/Chopper: I see, Miracle Current!
Nami: Why don't you just stay quiet and just ride along!!
Brook: Nami-san! Wanna sing?
Robin: Nami! It's becoming visible as you're talking
Franky: Oh! Where's this miracle current!
Luffy: Current that flows up to down? What's it like?
Oh!!! Is that it!? WoW!!!
Franky: Well done, mother nature!
Sanji: What in the world is that....?
Nami: That is the downward current plume...
Robin?: This is like an underwater....
(I assume next page starts with "waterfall!")
The Kraken pic
Crew: !!? Whoaaaaa!!! It's a KRAKEN!!!
Franky: Look, he's crushed many ships!! The ships that set sail in the last few days must have been caught!!
Usopp: Holy crap it's huge!! Monster Octo!!
Cariboo: I don't know where it came from...!! It's feeding on ships trying to get on the downward current! I've never heard of this before..!
Please, I don't want to die!! Turn back!! If you wait a few days, I'm sure that monster will...
Luffy: Oh, just shut up!!
Luffy: I got a good idea!! Let's tame it!