A lot of people have called out some interesting things - one thing that I notice is how the cold water ports shut down in the winter (in the northern hemisphere). It's one of those things I've always heard and known about, but to see it visually conceptualized (and the implications on economy and national interests) is very cool
One of the notable seasonal events here in Minnesota is the last barge of the season before the Army Corps of Engineers closes the locks on the Mississippi River. Then again, each spring, the first barge though is celebrated when the locks open again.
It's not earth-shattering, but it generally makes the news ;-)