Board Thread:Speculation House/@comment-34633327-20180112165111/@comment-30530552-20180114205345

The other issue at hand might be the presence of aquatic Grimm. Qrow said Vale was protected from Sea Grimm because of shallow waters, but by going east from Anima to Vacuo, I would presume that's deep ocean. Which means you get things like the Volume 4 Sea Dragon cranked up a notch.

We also don't know the distances between Vacuo's territory and Mistral's (since they've neglected to give us anything measurement-wise other than a few arbitrary ones with no scale to put it against) and how much fuel a ship or airship would need to go between kingdoms like that.

The risks would be uch higher, because of the Grimm as mentioned before, and for the fact it's open ocean.