The cave of Karda Nui, “the world that feeds the world,” is so big it’s practically a universe in itself. The bottom of the cave is submerged and enormous, strangely shaped stalactites have dropped from the ceiling and impaled on the floor. In the center of the cave, the last remnants of a once fantastic waterfall have exhausted themselves, creating a vast swamp far below. The water of Karda Nui is a mixture of liquid protodermis and saltwater.
The waters emit light at the center, as well as heat. During the time the waterfall was active, ripples on the water shaped the stalactite formations. Occasionally, pieces break off the rocks and fall into the swamp.
High up in the cave, the air is good and visibility excellent, but the closer you get to the swamp, the more difficult it becomes to see. The air down below is shrouded in mist and fog.
Each of the stalactites is almost a world all its own, with some being inhabited by Av-Matoran. The foundations of the stalactites are fragile and escape from them is virtually impossible … unless you can fly.