Devil's Thumb, Mountain summit in Avannaata, Greenland.

Devil's Thumb (Kullorsuaq in Greenlandic, Djævelens Tommelfinger in Danish) is a pinnacle-shaped mountain rising 546 m above the central part of Kullorsuaq Island in Melville Bay, northern Upernavik Archipelago. It stands about 3 km north of the Kullorsuaq settlement. Arctic navigators know it as a landmark similar to the Melville Monument further north, but larger.

The mountain has guided Arctic seafarers through Melville Bay for generations, serving as a critical landmark for ships navigating northern Greenland waters. This navigation role established its importance in the history of Arctic exploration and maritime trade.

The peak is known as Kullorsuaq in Greenlandic and holds importance as a natural landmark that shapes how local communities relate to their surroundings. People living on the island use it as a point of reference when describing their home and navigating their landscape.

The mountain is located about 3 kilometers north of Kullorsuaq settlement and is accessible by boat to the island. Climbing requires Arctic experience, proper mountain equipment, and preparation for harsh weather conditions that change rapidly.

Devil's Thumb is a familiar landmark for Arctic navigators, comparable to the Melville Monument farther north but larger. Its Greenlandic name, Kullorsuaq, is also the name of the island and the settlement 3 km to its south.