The Galapagos Islands are home to an incredible diversity and abundance of marine life. Three ocean currents converge here to form a unique phenomenon that causes an upwelling that brings nutrients and food up from the depths. Bait fish congregate in vast numbers and the larger predators arrive soon after. Hammerhead sharks swim here in massive schools that stretch as fas as the eye can see. By day, they drift lazily on the current as they rest one hemisphere of their brain. Not truly sleeping, they react to danger or to other stimuli, but they are relaxed and calm. By night, they are ferocious hunters that have little to fear. Solitary in their quest for food, they rely on keen senses and powerful jaws to locate and overcome prey. They are one of the apex predators in these waters. This scuba diver knows that he will be in no danger if he acts respectfully and does not give the sharks reason to become defensive or aggressive. They will regard him with curiosity, or even with indifference, but swimming out into the open among them would be taking this for granted. Instead, he remains on the rocks, watching one of nature's most magnificent shows. Better than an episode of Discovery Channel, or an Imax movie, this breathtaking scene unfolds before his very eyes. He would be unable to count the sharks as they pass within a few meters of his perch on the ledge. This wall of hammerheads numbers in the thousands. Humans are guests in this mysterious underwater domain. They are well advised to keep this in mind at all times.