Newhaven, East Sussex, England
This one is a few miles from me. You often see the Newhaven-Dieppe ferry as well as fishing boats, the lifeboats all cars coming and going from the car park.

Seaford, East Sussex, England
Again, just along the coast from me. Newhaven is to the right of this view, you might catch a glimpse of the ferry, or boats from the sailing club, plus folks on the beach. A storm was brewing in The English Channel when I took the screenshot!

Boat Nerd
A US site showing Port Huron, Marine City and Algonac all in MI. A little lower on the page is the Detroit, MI river watch cam too. Really enjoy this one, seeing all the huge ships going up and down!

As with the rail cams, if you know of any I should be checking out, please let me know!