Each spring, hundreds of great white sharks travel thousands of miles to gather in one specific part of the Pacific Ocean—halfway between Hawaii and Baja California. Scientists call it the Shark Café, though no one knows exactly why the sharks are there.

Some theories suggest feeding; others, mating rituals. What’s strange is that the area doesn’t seem especially rich in food. And yet, year after year, they return—sometimes diving to extreme depths and staying for months.

Whatever they’re doing, it’s clear: even apex predators keep a calendar.