6. What geographic reason explains why Russia would not have many usable harbors on

its long northern coastline?

Latitude

Explanation:

Russia is located at a very high latitude, and it's northern coast is entirely on the Arctic Ocean. Due to the extremely cold conditions found above the Arctic Circle, there are very few ports that are usable year-round due to the formation of sea ice. One of the few exceptions to this rule is Murmansk which benefits from the moderating waters of the Atlantic Ocean.