The second area of Mariana's Veil is frozen over, which makes sense in such depth. But to go even deeper, you need to get the next upgrade for the Submarine. In order to do so, you need to learn how to get the Cryoskin in Fisch first.
Where to find the Cryoskin in Fisch
The Cryoskin is part of the Challenger's Deep Bestiary. Challenger's Deep is the second area of Mariana's Veil which you can reach after you get the Heat upgrade. The Inferno Hide can be the most difficult part of collecting it if you don't have the right rods and bait, but once that's done, you can go down to the next area.
Once you get out from the Submarine, head down the path forwards. Go past the tent and the teleport back to the surface and you'll find a pool where you are going to fish (not in the pool where you arrive with your submarine). It is quite a long walk down this path so be prepared to be left alone with your thoughts. When you see the Challenger's Rod (740, -3350, -1530), you'll know you've reached the correct area.
The Cryoskin is a Common fish, so you should try to get it in the same way as the Inferno Hide. Put on the Garbage bait on one of the worst Rods you own, so that you decrease your luck as much as possible. Don't forget to take it off once you actually get the Cryoskin, or you'll futilely be trying to get the Frozen Leviathan and failing (it took me too long to realize).
How to Use Cryoskin in Fisch
The Cryoskin is one of four items needed to get the Ice upgrade for the Submarine. If you want to get even lower in the Mariana's Veil, you will need to get all of these items.
After you've fished out everything you need, head back towards where you first arrived and craft the Ice Upgrade, as well as the Glimmerfin Suit Lvl2 to make your way into the Abyssal Zenith.
For all information that you need to explore Mariana's Veil and get all the fish, I suggest checking out our Ultimate Fisch Mariana’s Veil Event Guide right here on Pro Game Guides.
