I don’t know why we were there, after multiple Westpacs things get fuzzy...but
I was on the USS Benjamin Stoddert in a Destroyer Group with USS Turner Joy in the north Pacific cruising the strait between Hokkaido and Russia.
We had ice parallel to the waterline the entire length of the ship. It was most pronounced on the superstructure all the way up to the signal bridge and antennas aloft. And that was from salty sea water at 20deg or less.
Gets friggin’ cold up there.
Hokkaido does indeed that’s up the northern part of the isles - Sasebo is down around just north of Nagasaki.