Slipping into the water, I swam shoreward where I could see iguanas occasionally surfacing. I watched as an iguana took a breath of air then dived down, tucking its legs close beside its body to streamline itself and using its long, broad tail in crocodile-like strokes to drive itself downward. Once on the bottom, it used the strong, recurved claws present on all its feet to grip the rocks on the ocean floor. I followed it down, but found myself unable to hold still against the rush and pull of the current as the swell pushed through the rocks. I was slammed backwards into and then over a boulder, to be sucked down again in the eddy created on its far side. Desperately, I held the glass-domed camera housing high above my head to avoid what would be a lethal battering. Rising to the surface, I swam hard for deeper water where the effect of the waves was lessened.

The iguanas shared none of my anxiety or concern. Using their hook-like claws, they moved securely underwater, over the tumbled-boulder bottom, seeking patches of red or green algae on which to graze. Finding a patch to their liking, they lowered their cheek to the rockface and used their rows of sharp, tricuspid (three-pointed) teeth to scrape the low-growing algae off the rock.