Sanctuary Four was an inhabited planet, located in the Milky Way Galaxy.

This class M world had an oxygen-nitrogen atmosphere. Massive bodies of water covered big portions of the planet and it had a forested surface environment. The trees had pink leaves.

It was home to a sanctuary for the endangered trance worms. Access to this world was granted when a code. Cleveland Booker worked with the personnel at this sanctuary in saving the trance worms and, by 3188, he had successfully brought in at least two of them.

By the 33rd century, Burnham and Booker had established their family home on Sanctuary Four.