On level 6 with Bart, drive to Planet Hype (right at the beginning of the docks, there is a revolving planet there) and go on the roof. Hop up to the very top and shimmy around the ledge. Hop out and run up to the first set of crates. Park your car next to the little gap/walkway on the left. Jump through the Globex sign and drive to the top. When playing as Lisa, drive any car to the pier and look for the huge oil tanker with a Globex sign on one side with a jump in front of it. Directly next to the fountain is a green monster truck. When on Apu's level, you can get a monster truck, Go to Springfield Stadium. Note: You can also ride the monorail in Apu's level. Go on the left side of it and you will see a blue ATV. You will see a card floating on the top of the trailer. In Marge's level, go to the trailer park short cut then go near the end of it. It is between two trailers at the far end. You can find an ATV or Quad to ride at the trailer park in Homer's and Marge's levels.
If it was done correctley you will be able to drive on the ocean. Use the horn super jump onto the waterfall. Next, go to the bridge leading from the observatory and you will see a small waterfall. If you activate the horn super jump then go to Lisa's or Bart's level (the one with the huge jump leading to the Squidport).
