This is a Lobster Pot (Trap) found washed ashore at the southern tip of Mt Desert Island. Bait is secured therein, the is lid closed (missing from this battered Relic) and the Thing is heaved into the shallow Sea with a marker Buoy attached. The Lobsters, smelling Dinner, crawl into the inner chamber (bottom of the PIC) and can't find their way out again. Their misfortune, our gain. Obviously, someone must tend these Traps. Enter the Lobsterboat&Crew.
All along the Maine Coast, at any given time several boats may be seen working immediately offshore.
They work their way along in a series of loops connected by short straight runs. During each loop an appropriately marked buoy is snagged and by winching its line the attached Trap which had been resting on the sea floor beneath is brought aboard. The dark object on the side of the boat is a Pot being drawn up.
Again the dark object is a Pot. Any appropriate sized Lobsters found therein are kept to end up in Supermarket Tanks. Notice that while some Folks Work, others Play.
The Maine Lobsterboat Men and Women (i.e. the Deckhand in this PIC) think nothing of working very close in to those Rocks.