Donut Plains 2 is a level seen in Super Mario World. It's a underground auto-scrolling level seen in the world, Donut Plains. The level also features some yellow platforms that can crush Mario or Luigi.
After getting to the end of the underground section, enter the Warp Pipe and you'll see the goal gate. Pass it to complete the level. However, if you up the fourth Warp Pipe on the section with the four yellow platforms and four pipes, when you enter the secret area, go to the nearest pipe. Then, enter it and you'll see the goal gate.
For this one, the player must have Yoshi or a Cape. Then, the player must enter the secret room like above. For Yoshi, they must use the Blue Shell, and fly up to the key. For Cape Mario or Luigi, they must fly up and land where the key is.