That would be the nautical equivalent of "An UNhappy return" if you ignore one. I guess that's a good reason to STAY away from an unlighted return.

I've seen occasional meterological and "scientific" floats that aren't lighted or don't have their lights visible.

There are all kinds of fishing buoys which don't show-up on radar unless you have it on 1/8 or possilby 1/4 mile -- who does that offshore in any normal situation other than VERY dense fog. Nuns and cans don't make a noise -- but usually will show-up on radar unless you're in a horrible seastate.

On the Chesapeake, occasionally the bell buoys in the vicinity of the Sassafras have Osprey nests. I hit one once on a moonless night at the beginning of a month cruise. In retrospect, it was right where the chart plotter said it was. :^))) I was asking the crew member on watch with me, "Where's that bell buoy? I can't spot it's light!"

Then the buoy "spoke up". (It should have been noted on the chart: "Light with Bell will ring and go boom, if hit". After the Close Encounter of the Fourth Kind, we sailed-on up from the Chesapeake to Newport/Block/Marthas Vineyard/Nantucket/etc., and back. I couldn't see any real damage from the bow when I looked down underway. In Newport, they suggested that I have it looked-at when we got back. We ad the little boo-boo from the that 10' big channel bell buoy made on the boat fixed as soon as I got back.

We cut-off the outer skin of the 18" round section off the hull which was crazed a bit, epoxied the crushed balsa core behind the impact point,reskinned and awlgripped the bow section around the area. My bride still reminds me of the noise that it made below; and, the image in my mind of the bell sliding by the boat was certainly disconcerting.

I've sinned before, luckly that time it wasn't worse. It renewed my committment that when in a boat, DO NOT get close of objects I can't see, otherwise can't positively ID, or don't understand what they might be. Those objects include, cans, floats, fishing boats dragging lines, and now abandoned gantry towers.