User blog comment:ChishioKunrin/Volume 6 Bingo/@comment-4141313-20180807135123/@comment-4141313-20180808024959

I doubt they'd fully head north. Comparing the location of Haven Academy on the map to the coasts, their quickest point of exit would be if they crossed the waters between Mistral and the Northwest coast.

If they headed North they'd cross through Windpath but they'd have to traverse the Tundra, and if they headed South then West they'd be taking quite a detour. But they can bypass all of that by traversing the waters between Haven and the Northwest. Its landlocked so bigger Sea Grimm wouldn't be able to come in from the ocean, and the smaller airborn grimm could be taken care of with Crescent Rose's sniper, Ember Celica, Weiss' Lancer Summon, and Magnild's Grenades.