And this is among the images we had hoped to encounter at world-famous Darwin's Arch. We wouldn't be disappointed.

We began this dive before 7 a.m. and in a short 44 minutes at around 80 feet we had seen dozens of very large hammerheads, often lined up like this to be cleaned. If you peer carefully through the turbid water of this picture, you can count eight sharks. They seemed unconcerned with us as long as we sat fairly still.

Many of these sharks exceeded six feet in length. They are massive but lean and efficient in the water. Mostly, they were leisurely and deliberate in their motion but if something startled them, one quick whisk of the caudal fin and these large animals disappeared over the rocks or into the imperfect visibility.