How do scientists know how deep a sperm whale goes? They used digital tags to study 198 foraging dives by 37 sperm whales in the Atlantic Ocean, the Gulf of Mexico and the Ligurian Sea.

Sperm whales dive deep down in the ocean to find food. A sperm whale can dive deeper than 3,000 feet (about 1,000 metres), and sperm whales often dive down to about 2,000 feet (600 metres).

Their deep dives last about 45 minutes on average, though a sperm whale can stay underwater for an hour or more. Sperm whales are usually found in water at least 1,000 metres deep.

A deep dive puts the body under heavy water pressure, and a sperm whale's ribcage is flexible, so its lungs can collapse safely under that pressure. Its muscles hold extra myoglobin, a protein that stores oxygen.

A sperm whale eats mostly squid. It eats about one ton of food in a day, and it eats about 3 percent of its body weight each day.

Sperm whales make clicking sounds and use echolocation to find food. In echolocation, an animal makes a sound that travels through the water, bounces off an object and comes back as an echo.

The sperm whale is the largest of the toothed whales, but the blue whale and other large rorquals are bigger. An adult male is 49 to 59 feet (15 to 18 metres) long and can weigh up to 45 tons, while an adult female is up to about 40 feet long. The head is about one-third of the length of the whole body.

Adult male sperm whales usually live alone, except in the breeding season, and young males leave their family groups and live with other young males. Males often do not take part in breeding until their late twenties.

Female sperm whales and their young travel together in groups, and the females help look after the young together. A mother carries her calf for 14 to 16 months before it is born, and the calf nurses for two years or more.

Commercial whaling from about 1800 to the 1980s greatly reduced sperm whale numbers around the world. The International Whaling Commission placed a moratorium on commercial whaling in 1986.

Underwater noise from human sources can interrupt the normal behavior of sperm whales, which rely on sound to communicate. Sperm whales can also become entangled in many different types of fishing gear, including trap lines, pots and gillnets.

As of November 2026, the sperm whale is listed as endangered under the Endangered Species Act in the United States. NOAA says sperm whale populations are still recovering and their numbers are likely increasing.

Words to know

• foraging: looking for food
• echolocation: finding by sound
• moratorium: official pause
• entangled: caught up
• gillnets: fishing nets