MarineTraffic is an open, community-based project, which provides real-time information on the movements of ships and the current location of ships in harbours and ports.
A part of Marine Traffic functionality is a density map that shows how many vessels sailed in a particular region per year. You can observe, for example, how sparsely visited are higher latitude areas compared to more popular routes. Why this is useful? First, you get an idea of how many ships are expected around and second, weather forecast models generally work better in areas where there is more commercial traffic as ships send regular SYNOP messages en route that is used as input data for the models.
https://www.marinetraffic.com - click “Density Maps” on the left pane