Spiral is found in world 6 and in advanced challenge mode in Super Monkey Ball Deluxe. It begins with a long bridge leading to a path jutting off to the left and the entrance to the spiral at the right (the path at the left serves as a run-up). The spiral descends slowly and ramps to the center, meaning that the player must go fast to keep enough centrifugal force to stay on the path (incidently, similar to the level centrifugal). The path at the beginning has some bananas and a banana bunch sits behind the goal (which can be reached if the goal is crossed fast enough).
Similar levels
A level in world 8 of Super Monkey Ball Deluxe (called spiral hard) is a titular, harder version of spiral.