Wall of jacks pass scuba diver like a long freight train

Divers perched on a ledge against a rock wall witnessed a beautiful and unusual sight as a long procession of big-eyed jacks passed in front of them. This is the wall beside Darwin's arch, one of the world's most legendary dive sites in the world. Scuba divers come here to swim among the Galapagos sharks, the huge schools of hammerhead sharks, and the whale sharks.
The sharks come to these warrants due to the convergence of four major ocean currents. These currents create an upwelling of nutrient-rich water from the deep. Bait fish come here in huge numbers to feed, bringing the other predators with them. Some of the largest sharks benefit from the cleaning stations. Trevallies and silky sharks eat remoras off the whale sharks. Smaller fish pick off parasites. It's a complex web of interdependency and all species benefit in some way.
These jacks travel in large schools to help them evade predators. When a group this massive passes over or around scuba divers, it can create an effect similar to an eclipse. Light is blocked out and there is near darkness until the fish have all gone by. Their shimmering scales provide a mesmerizing effect that is beautiful to behold.