The group didn't immediately leave the sea. The white waters contained chaotic laws, which made them one of the best resources in the entire higher plane.
Noah and the others remained on the shores for a while. They even fought the many packs that arrived to challenge them for the ownership of those regions. Those attacks eventually featured a rank 8 magical beast in the middle tier, which forced them to run away before that force reached those lands.
The group took a different route to return to the human domain. They still wanted to fight and improve, so they decided to avoid the regions already conquered in the first part of their journey.
Most of them now had new packs since the Foolery made every region that they inhabited irresistible. Still, Noah wanted to find more troops and valuable resources, so their return led them into unexplored areas.