Underwater World was an area in Plants vs. Zombies: Journey to the West and later in Plants vs. Zombies: Great Wall Edition, and is the sixth area exclusive to the former's Adventure Mode. This area took place in an underwater palace, presumably in the East Sea.
This area was completely water-logged with sun falling in a serpentine pattern rather than directly down, and plants requiring the aid of Oxygen Algae to remain planted. When not in the vicinity of an Oxygen Algae, plants will slowly drown and take damage until either defeated or when an Oxygen Algae is planted nearby.
- This is the first area exclusive to Journey to the West to add new plants.