[1][2][3] Of the three towns which make up the municipality, Keflavík is the largest, while Hafnir is the smallest and some 10 kilometers distant.

Keflavík and Njarðvík were originally distinct towns but gradually grew together over the course of the latter half of the 20th century, until the only thing separating them was a single street.

[4] In 2006, when the United States Navy closed Naval Air Station Keflavik, the site was taken over by the development agency Kadeco, and renamed Ásbrú.

The Suðurnes region, which includes Reykjanesbær and five neighbouring municipalities, was home to 27,113 people; that is about 7.6% of the country's population.

[7] Reykjanesbær has a subpolar oceanic (Köppen: Cfc; Trewartha: Eolk), with temperatures rising above 10 °C (50 °F) only in July and August.