Grímsey is the northernmost inhabited Icelandic territory; the rapidly disappearing islet of Kolbeinsey lies some 60 km (30 nmi) farther north, but has never been habitable.

Grímsey has an area of 5.3 square kilometres (2.0 sq mi), and a maximum elevation of 105 metres (344 ft).

As of 2020, the place where the line crosses the island is close to the northern tip and by the middle of the 21st century it will pass north of Grimsey altogether.

[5] In 2017, a movable monument – an eight-tonne stone sphere dubbed "Orbis et Globus" – was placed on the circle, and is periodically moved to the corrected location.

[9] Despite the northerly latitude, the climate is generally mild because of the North Atlantic Current, which brings warm water from the Gulf of Mexico.

[14] The island has been designated an Important Bird Area (IBA) by BirdLife International because it supports large seabird breeding colonies of black-legged kittiwakes, Atlantic puffins, razorbills and common murres.

It has a community center, a shop, a library, a public indoor swimming pool, and a school from kindergarten to grade 8.

[17] On learning this in the 1870s, American scholar and keen chess player Willard Fiske took an interest in Grímsey, sending supplies, supporting the economy, and leaving money in his will, though he never visited the island.