It lies in Hinlopen Strait northeast of Cape Weyprecht on Spitsbergen.

The island is a low basalt cliff and its highest point is only 10 meters (33 ft) above sea level.

The wildlife consists largely of polar bears.

The island was discovered in 1867 by the Swedish-Norwegian polar explorer Nils Fredrik Rønnbeck.

It is named after W. Simonsen (or Simonson), a Norwegian navigator that helped explore the Kara Sea in 1871 on board the Sleipner.