One morning in Caye Caulker, Belize.
I had been skin-diving at this pier for several days, from early morning till dusk, getting astonished at the variety of marine life I was seeing for the first time (I live in a country where the sea is freezing cold due to the Humboldt polar stream, and underwater life is not so colorful), and sometimes I noticed those large snails crawling on the sandy bottom; I followed them as much as I could hold my breath, and became an 'expert' tracking them. One of those days, I stumbled on an empty shell at some 5 meters deep, so I dived, grabbed the shell, and carried it to the surface using the risky and somewhat painful technique of putting it between my swimming short and my skin (children: don't do that at home).
I left it drying on the pier, and saw that it was a good picture too, so I made the image shown here.
I used a Nikon FM2N, 20 mm. Nikkor lens, f.16 set for hyperfocal, 1/30 sec., polarizing filter. Film was Fujichrome Provia 100 Professional slide film.