Physeter macrocephalus

SIZE: Male- 14-16.5m, Female- 10.5-12m (though females not seen off Iceland)

The sperm whale is the largest toothed whale and considered the largest predator in the ocean. There are many amazing facts about sperm whales: their ability to dive to great depths of over 2,000 metres, hold their breath for up to two hours, and their enormous brains. They are also the only whale species known to have wrinkled skin, although the reason for this is still a mystery.

There is a large difference in size (sexual dimorphism) between male and female sperm whales, with males growing up to 40% larger than females. Sperm whales are found throughout much of the world’s oceans, but they are not commonly seen from whale watching boats because they live in very deep water, which is often too far offshore for regular whale watching.

Sperm whales also have a fascinating social culture. Females live together in close-knit family groups throughout their lives. They produce powerful clicking sounds inside the huge organ that makes up much of their head. These clicks are used for echolocation when hunting at depth, but they also form patterns known as codas. Codas are sequences of clicks that are unique to different family groups and clans. Two clans can live in the same area but rarely socialise, generally associating with other groups that share the same coda patterns.

Male sperm whales begin life in warmer waters with their mothers and family groups. At around 8 years of age, young males leave their mothers and may travel with other juvenile males. They head towards colder waters, where food is more abundant, and continue feeding and growing until they reach sexual maturity at around 20 years of age. Adult males may then move between warmer waters, where they encounter females, and colder feeding grounds.

Sperm whales were once heavily hunted for spermaceti, the valuable waxy oil found in their enormous heads, which was used for candles, lamps and lubricants. Their global population is estimated to have fallen from around 1.95 million before large-scale whaling to about 845,000 today. Although populations have been recovering since commercial whaling largely ended, sperm whales remain classified as vulnerable globally and continue to face threats such as fishing gear, ship strikes and underwater noise.

In Breiðafjörður, we mainly encounter male sperm whales, often bachelor males. They can be found in the deeper parts of the fjord, particularly during spring and early summer. Láki Tours is the only whale watching operator in Iceland that regularly encounters sperm whales.