From the Super Mario Wiki
Riverside Park is the third race course of the Mushroom Cup in Mario Kart: Super Circuit. It takes place in a forest near a river. Its music is full of various animal noises. Lakeside Park functions as a more difficult counterpart to it, and uses a remix of its music.
After the first turn there is a straight path then the player come across the first crossing of the river. There is a spot on both sides of the river where there is a bridge. There are crash barrier squares that block some potential shortcuts. Shortly after the first crossing, the player actually goes over the river. There is a U-turn here and a shortcut (see "Shortcut" below). The player goes around a road branch in the river and goes around another U-turn, and from there the player goes straight and cross the river to the final stretch: a loop around where the player jumps over the course, as pictured below.
After the player jumps over the river, on the first U-turn, if they turn about 100 degrees and drive to the river, there is a narrow pathway across the branch.
Also, after the very first U-turn, the player can use a mushroom to go over the water and go underwater to a dock.
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