I didn't realize there were so many.

The two states I've been involved with boats (RI and FL) both require hull numbers for registration stickers (ie: a title). No reg or expired stickers here in FL and the Woods & Water Cops (
FWC) will be pulling up along side and probably ticketing you "for the cause" (conservation). Trailers are registered separately.
A few years after I moved here, I borrowed my brother's 12' alum. boat to take a little cruise in the St. Johns River with my daughter. I had sold my inflatable a year earlier but still had the 8hp off it. That boat was registered in RI and I had done many a trip up and down the St. Johns with it not once "pulled over" by FWC. The 8hp was a good match for the 12'-er.
Not 5 minutes on the water and FWC pulled up, did a safety check (passed) then informed me the boat needed to be registered to be on navigable waters.

He did say I could go over to an area where he had just seen some manatees so I could show my daughter and we motored over there but there were none.
The first month here, I had probably seen a dozen alligators in the wild--it was probably 5 years before I saw a sea cow. I'd like to try the flesh from both although I would imagine manatee steaks would be overly fatty and "marbled".

Probably like eating a sloth...
Anyhow, I looked into getting the boat registered. It was a land-locked "lake" boat that came with a house my brother bought so he and prior owners had never bothered to register it. It had been over 10yrs since it was registered and to title it would require hunting down the previous titlee, which I did, but who was non-responsive. That was the extent of my involvement with that boat other than using it on my brother's lake.