Which octopus lives at the deepest depths?

Grimpoteuthis is a genus of pelagic umbrella octopuses known as the dumbo octopuses. The name "dumbo" originates from their resemblance to the title character of Disney's 1941 film Dumbo, having a prominent ear-like fin which extends from the mantle above each eye. There are 13 species recognized in the genus. Prey include crustaceans, bivalves, worms and copepods. The average life span of various Grimpoteuthis species is 3 to 5 years.

Most species of Grimpoteuthis live at depths of at least 3,000 to 4,000 metres (9,800 to 13,100 ft) with some living up to 7,000 metres (23,000 ft) below sea level, which is the deepest of any known octopus.

They are some of the rarest of the Octopoda species though they occur worldwide including in the waters of New Zealand, Australia, Monterey Bay, Oregon, Philippines, Martha's Vineyard, Papua New Guinea and Azores. The largest dumbo octopus ever recorded was 1.8 metres (5.9 ft) in length and weighed 5.9 kilograms (13 lb). The average size for most species is 20–30 centimetres (7.9–12 in) in length. The average weight is still undetermined.