Why do whales strand themselves on beaches?

Nobody knows for sure, and that is the honest answer. Several explanations have been proposed, including changes in water temperature, problems with whales' echolocation in certain surroundings, and geomagnetic disturbances, but none has so far been universally accepted as a definitive reason. One link, though, has been found: between mass beachings of beaked whales and the use of mid-frequency active sonar.

Some whales are far more at risk than others. The whales that mass strand are mostly toothed whales that live in deep water in large, tightly knit groups. That social bond matters: if one whale gets into trouble, its distress calls may prompt the rest of the pod to follow and beach themselves alongside.

Beaching is deadly. Beached whales often die from dehydration, from collapsing under their own weight, or from drowning when high tide covers the blowhole. Yet people have always seen it, and humans were salvaging from stranded sperm whales in southern Spain about 14,000 years ago.

Not every landing is a tragedy of confusion. In Argentina, killer whales hunt seals by intentionally beaching themselves, then riding the next wave back into deeper water. And many stranded whales have been rescued, by keeping them cool and wet until high tide.