When they reached the shore, “he went that way, and I went that way,” Lerner added, chuckling to himself.

So it goes for the North Shore lifeguards of the Ocean Safety and Lifeguard Services Division on Oahu, a group of 42 full-time workers given the task of patrolling one of the most dangerous stretches of beach in the world. Called the Seven Mile Miracle, Oahu’s North Shore attracts both pro surfers and amateur swimmers to tangle with the massive swells that roll in frequently during the winter. In 2013, there were more than 1,000 ocean rescues and major medical cases handled by the guards on the North Shore.

The duties of the department are as varied as the surf here, and the patrol has evolved from a few lifeguards wandering the beach with a buoy in the 1960s to a tiered, role-specific system with seven staffed lookout towers, four mobile units and two personal rescue watercraft, or “skis,” patrolling the northern coast.

Each guard has a rank and a task on the force, akin to the structure of a fire department. There are those who patrol the beach on all-terrain vehicles, others who man the lookout towers, and those able to navigate the waves and current, making saves with only a buoy or a board. The most experienced guards drive the skis, the 1,000-pound personal watercraft with rescue sleds attached to the backs.