Lethe (The Parliament of Rats)

Lethe was an ocean planet, named after the mytical River Lethe. The world's time field was full of striations, meaning that time-sensitives were required to navigate the waters. Humans lived on the islands of the world.

After the Lethean Campaign during the War in Heaven, (PROSE: The Book of the War) the Time Lords left the planet ravaged by time fractures which eventually pulled in the Doctor's TARDIS, with the Fifth Doctor and Nyssa being rescued by the crew of the Lung of Heaven. (PROSE: The Parliament of Rats)

Lethe (The Parliament of Rats)