Go into the design-a-park mode. Now, use the water tool and make an area with water and next to it make an area of water one that is sunken into the ground (using the L button, make it lower). Now, play the park. You'll be able to grind the corner where the water drops down although you're not supposed to be able to go through the water. If you put more water in front of the grinding area, you'll run into it after the grind and die. You can do this with lava, but you can only grind certain edges of lava. It's hard to grind the spikes.
Submitted by: Connie