After clearing the Strong Strom Canion, the Conquerors went outside and immediately came back in the dungeon to challenge the Frozen Tundra next. Rein had no idea which of the remaining areas might have the sleeping god, so he did not think much about it and decided to challenge the Frozen Tundra next.
As the name suggested, this area was covered in snow and there was always snow falling from the sky in this region. The cold of this place is freezing and a person needed specialised equipment to survive it.
Even then this area was quite famous and several gold or silver ranks also came here frequently. That was because at the outer edge of this area where it was connected to the Sunken Ruins, a special type of flower called Blue Light Fristua bloomed.