From Halopedia, the Halo wiki
Derelict is a multiplayer map in Halo: Combat Evolved. It is set aboard a Forerunner space station apparently in orbit around Threshold, as the planet is visible through the windows, as well as the moon Basis. It is cataloged by the UNSC as Deep-Space Anomaly #0198. It is a very small level that is best suited for 10 or less players, as more can become extremely chaotic unless that is the desired effect.
Derelict is a small, symmetrical map where battle is fast and furious. The four pillars near the center of the map support a cross-shaped system of catwalks. These catwalks are accessible only by teleporter. The catwalks make excellent sniping or grenade-throwing positions, though standing still at any place on this map means inviting a swift death.
In the center, on the upper level is an overshield, on the lower level is a Health Pack. The active camouflage is on the upper level between two lights. The sniper rifle is on the area exactly opposite the Active camo before three lights.