Get 2700 points in the trick skill game.
Collect all Gold Cups on tracks 1 to 6, and you will be rewarded with the desert track, Quicksand Valley, and an additional snowboard.
First you must earn gold cups on tracks 1 to 7 to open
up Quicksand Valley. Now go for the gold on Quicksand Valley, and Silver
Mountain will open up.
First you must earn gold cups on tracks 1 to 8. After you opened up Silver Mountain, come in first to get a gold cup and you will be treated to an ending sequence with all the characters. Track 9, Ninja Land, will now be open.