[4] A mass concentration (mascon), or gravitational high, was identified in the center of Mare Crisium from Doppler tracking of the five Lunar Orbiter spacecraft in 1968.

[6] By the 17th century, Mare Crisium had acquired the name 'Caspian Sea', being labelled as such by Thomas Harriot, Pierre Gassendi and Michael van Langren.

Ewen A. Whitaker speculates that it received this name because it occupies roughly the same position on the Moon's face as does the Caspian Sea on Earth, with respect to maps of Europe, North Africa and the Middle East.

[7] Mare Crisium is just visible from Earth with the naked eye as a small dark spot on the edge of the Moon's face.

Three hundred miles in diameter, and almost completely surrounded by a ring of magnificent mountains, it had never been explored until we entered in the late summer of 1996.In Warhammer 40k, it is the location of the Somnus Citadel a base for the Sisters of Silence.