Erebus is a crater on Mars visited by the Opportunity rover on the way to the much larger crater Victoria. It is named after the polar exploration vessel HMS Erebus. The rover was in the immediate vicinity of the crater from approximately sol 550 to 750 (October 2005 to March 2006).
Erebus is located roughly 2,500 meters south of the much smaller crater Vostok, which was previously visited by Opportunity. It is surrounded by what scientists are describing as "etched terrain", a region where rocks peek out from under the sand of Meridiani Planum.
Erebus is about 350 meters wide, twice as large as the crater Endurance. However, it is very old and eroded, and is barely visible from the ground; it appears merely as a number of flat rocky outcrops encircling a region of dunes.