More can definitely be said, but you might want to check out this answer I wrote about convoys to the USSR along the North Pacific route.

In short: there definitely was a North Pacific sea route, plus an air route (ALSIB). The major issues with using this route were: both got supplies to the remote "wrong" end of the USSR compared to where they were needed, and required extensive transportation across the USSR once delivered. Also the USSR and Japan were not at war with each other until August 1945, while the US and UK were at war with Japan, so supplies sent by sea had to be carried by Soviet merchant vessels.