Covenant Ship

Covenant Ship was a planned level in Halo 2. The level was set to take place after Cairo Station, on a Covenant Assault Carrier, and would have served as Miranda Keyes's main introduction.

Content
After opening the airlock of the Cairo Station's docking bay, the player would be blasted toward the Covenant ship and boarded it instead of destroying it with the bomb. This level would have involved infiltrating the Covenant ship, taking on and killing its crew and eventually stealing a Wraith and end up destroying the ship by bombarding its power core with the Wraith's mortar.

As mentioned by Joseph Staten, Miranda Keyes and her ODSTs would have also been onboard the ship in order to help you and may have played a big role in the eventual outcome. This level however was cut due to time constraints and replaced by a cinematic that created "just as much work" for Bungie Employees.

Trivia

 * The Covenant Bomb was added in order to destroy this ship without needing the level and find a reason for John-117 to open the airlock.
 * In the Halo 2 Announcement Trailer, John-117 is clearly seen jumping from Cairo Station without a bomb, which is consistent with the existence of this level.