During Columbus’s second Caribbean voyage in 1494, green sea turtles were said to be so numerous that his ships nearly ran aground on them; apparently, his crews could almost walk to shore on their backs. At that time, the green sea turtle population in the Caribbean was estimated to be as high as 660 million adults. Today, the species is endangered, with the global population hovering around 100,000 nesting females. Targeted fisheries, bycatch, and coastal development have taken a heavy toll. Although I will never get to experience the number of turtles that roamed the Caribbean in 1494, the ones swirling around my head  near Little Farmer’s Cay in the Bahamas where I made this photograph, helped me imagine the wonder of our oceans’ past.