Caldera Lake
From The Thalassan Sphere
Caldera Lake is a naturally-occurring lake in the crater of Granfeu Mountain, a dormant volcano on Bitu en Sul and also the name of the town that rings the lake. The Caldera Academy is on the lake's shore. Until the Cataclysm, it was the home of the Sunstone. Although the stone was removed to the Sunspire and later destroyed, the lake still has huge manatite deposits and a fair number of strange creatures living in it.
Within the first few centuries of the founding of the Academy, elementalists dug a corridor between the caldera and the crater of Granfeu and founded Granfeu Townships, a collection of farming villages that exploit the rich, volcanic soil to great effect.