Cara Nui is an island that is now primarily a ruin scavenged by desperate matoran, after the death of their leader.
Cara Nui is a largly rocky land with cliffs along one half and rocky shores along the other. The west side was mountainous, while the east side was a volcanic desert, known as the Black Sands. There was never very much vegetation on the island, but on the north there was a vast forest on the slopes off some mountains.
It is inhabited by only Ta-Matoran, however they are devided into three groups: Fire Matoran, Lava Matoran and Ash Matoran. These are just small varients of the fire element, and no real difference occurs in their powers. The Fire Matoran lived on the mountains, the Lava Matoran lived near the shore where Lava surged out from under the island into the sea, and the Ash matoran lived in the volcanic desert. Also, there was one city in the centre were they all lived, and this was the home of their ruling Turaga.
This island was destroyed by Renegade Toa Member Zetus when he lured the Turaga (and the Turaga's battle mech) into a forest, claiming that there was a visitor from a different land. However, this was just an attempt on the Turaga's life. The turaga leapt into the mech, and they battled all the way back to the capital. Up until this point, Zetus had not used any of his powers. Having successfully tricked the turaga into thinking that he was powerless, he used his power over plants to throw a seed of a giant carnivorous plant to the Turaga's feet and accelerate its growth tenfold. Suddenly the turaga was faced with a monster that was taller than the mountains, and he was promply consumed, mech and all.