Rainbow Road is the last track of the Special Cup in Mario Kart Wii. Unlike other versions, this track contains multiple twists and sharp turns, as well as a steep drop after the starting line. The middle of the track features a Super Mario Galaxy-style launch cannon that blasts racers through a light tunnel to the final part which consist of two twisting paths before the finish line.
The track's background is an atmosphere and features the Earth.
The course begins on a near 90 degree slope, located after the starting line. Light drivers are easy to push off in this area, since there are no walls that can help the player from falling off. Three boost panels are present in this slope. One stretches across the road while the other two are spread apart from each other, such as one being on the right while the other boost panel is on the left, (depending on the mode of the race). After the slope is a ramp with a boost panel in it and a sharp turn left. Any vehicle that performs a trick has a risk of falling off on the right end; the worse the drift/handling rating, the more likely the player will fall off.
After the first curve are three more boost panels that stretch across the road and a half-pipe ramp on the very right, plus a turn left. The half-pipe contains floating item boxes for the player to use. After the left turn is a slightly wavy road, which the player may perform tricks on. Each lap, the road gets wavier, allowing for more tricks to be performed. After the wavy part is a ramp with a boost panel on it, for the player to speed up and perform a trick. The player will then see two giant holes that make a shape of the number eight. These holes will cause the player to fall. Half-pipe ramps are located to the left and right of these holes, and the player may perform a trick on the edges of these holes, since the edges of these holes contains small ramps. Both holes contain half-pipe ramps, but the latter one doesn't have any item boxes on top of it.
After this area is a turn left, then a curve right that has item boxes lying across the road. After the item boxes is the launch cannon which will lead the player at very high speeds through a light tunnel that follows after it. When the player gets out of the launch, there is a very minor twist in the road and a half-pipe ramp that leads into another section of the track, making a broad turn right for the player. After this particular ramp are two roads, which split and then merge later on in the track. Both will make the player end up in the same area, but one to the right is more elevated than the other and has boost pads in different locations. Both will lead to a ramp with two boost panels on it, with floating item boxes. Past the ramp is where the road merges again. This part has more boost panels with a sharp curve to the left and to the right. The boost panels may give the player an edge or throw the player off course and off the track. Past this area is the finish line, which starts the track over for another lap. It is the longest Nitro Course, and the second largest track in the game.