Planet (The Forgotten)

During the Last Great Time War, the Eighth Doctor was imprisoned for over a month on a planet.

From his cell on the planet, the Doctor he could see starships exploding in the sky. When he gained a new cellmate, Chantir, the Doctor managed to escape and steal the Great Key, which was kept inside the prison. The Doctor then released all the prisoners, which included Sea Devils among other species.

The Doctor then went to retrieve his TARDIS, which he had left a mile away from the prison. (COMIC: The Forgotten)