What's the largest animal gathering on Earth?

PEOPLE LOVE A PARTY. BUT AS POPULOUS as our species is, the headcounts at our gatherings don't match those of other species. The Maha Kumbh Mela, a Hindu pilgrimage in Prayagraj, India, drew more than 660 million people in January 2025. But this horde - thought to be the largest in human history – pales in comparison to the groups formed by our animal relatives.

- Richard Pallardy

The largest animal gatherings in the world likely occur in the chilly depths surrounding Antarctica. The Southern Ocean is home to Antarctic krill - tiny crustaceans that form swarms more than 20km long. A single swarm may contain trillions of individuals. Krill are a crucial food source for other organisms, including fish, penguins and whales.