World 3, Aquifer, takes place underwater. In addition to other gameplay elements, in water the player must pay attention to their breath timer, a countdown from 100 to 0 that is only restored by destroying underwater doodads and collecting the air bubbles released. If the timer hits zero, the player begins losing HP.
The background music in World 3 is Razor Girl.
World 3 demonstrates the first use of a fourth color in Downwell. In the default palette the additional color is blue (for water elements).
Normal World 3 enemies include: