The Cauldron

The Cauldron is the eleventh level of Sonic and the Black Knight that holds one of the four barrier stones.

Story
Sir Percival travels through this area to locate a barrier stone deep within the volcanoes. It is unkown what the barrier stone says.

Gameplay/Environment
It is probably called the cauldron due to the fact it is nothing but a pool of hot lava. Eventually in the game, a river of lava is surfed on, the player enters a field of geysers, and they also climb a large wall to reach the goal. There is also an abandoned village and crumbling towers swarming with the Knights of the Underworld.

Trivia

 * Despite the immense heat that the lava emits, the wood buildings floating in the area are not burning.