The polar region of Earth where, in 2153, a research team dug up wreckage and frozen drones from the Borg sphere destroyed during the events of Star Trek: First Contact.
The Arctic is the setting of the opening of the Enterprise episode Regeneration. When the Enterprise-E destroyed a Borg sphere above Earth in 2063, in Star Trek: First Contact, some of the debris fell in the far north and lay under the ice for about ninety years.
In 2153 a science team excavating the site finds the wreckage and frozen cybernetic bodies, which it thaws out for study. The drones revive, assimilate the researchers and leave Earth in a modified transport.
Enterprise chases the ship, which grows more dangerous as its crew adapts, and finally destroys it, though not before the Borg send a signal towards the Delta Quadrant. The story gives an in-universe reason for the Borg's later interest in Earth.