Oh, there it is

This morning, while canoeing among the Thousand Islands on a sunny summer's day, I saw in the water beneath the boat a black rubber ring, about 8 inches in diameter.

I knew exactly what it was: it was a slice of inner tube, used to keep a foam sleeping mat rolled up when packed. But my first thought was, "oh, that's where it got to!"

That's because one afternoon in Zihuatanejo, Mexico, on Christmas break of 1987, I was lying on a foam sleeping mat on a beach along the Pacific Ocean when I saw a young boy run by wearing a cool-looking black headband... and realized almost immediately thereafter that I would have to find something else to roll up my blue Ensolite.

Found it, finally. Works like a charm.