Swamp

A swamp or marsh was an area of land partially covered with shallow water. The Doctor encountered swamps on many planets in his travels, including one inside Vorg's miniscope (TV: Carnival of Monsters) and one in the Matrix. (TV: The Deadly Assassin)

Swamps on Earth
The Doctor said that both London and Venice used to be marshland. (TV: World War Three, The Vampires of Venice)

Redvers Fenn-Cooper once visited a swamp full of giant lizards like giant dinosaurs. (TV: Ghost Light)

The Eleventh Doctor, Amy Pond and Rory Williams visited a swamp in 1929 Louisiana. (COMIC: Terror from the Swamp) The Sixth Doctor and Melanie Bush visited a Louisiana swamp in 1957. (PROSE: Swamp of Horrors (1957) - Viewing Notes) The Eighth Doctor visited a Louisiana swamp in the early 21st century. (PROSE: The City of the Dead)

Swamps on named planets

 * Alzarius (TV: Full Circle)
 * Delta III (TV: The Power of Kroll)
 * Desperus (TV: The Daleks' Master Plan)
 * Diamedes (PROSE: Detour to Diamedes)
 * Gameworld Gamma (COMIC: The Hunt of Doom)
 * Gurnian (COMIC: Monsters of Gurnian)
 * Haunted Planet (COMIC: The Haunted Planet)
 * Ogros (TV: The Stones of Blood)
 * Sunday (PROSE: Wetworld)
 * Terroth (COMIC: Planet of Serpents)
 * Zom (COMIC: City of the Damned)

Swamps on unnamed planets

 * The Second Doctor, John and Gillian visited an unnamed swamp planet inhabited by giant spiders controlled by the Master of Spiders. (COMIC: Master of Spiders)
 * The Second Doctor, John and Gillian visited an unnamed swamp planet where they battled witches. (COMIC: Return of the Witches)
 * An unnamed swamp planet in the Calysteral cluster was used by the Judoon as a prison. (TV: The Vault of Secrets)
 * Sancroff was imprisoned on an unnamed swamp planet. (AUDIO: The Sirens of Time)
 * The Tenth Doctor and Donna Noble visited an unnamed swamp planet, where they were chased by tree-like monsters. (COMIC: The Time of My Life)