Quick start
Note: This trick assumes the game is under the default controller setting. Hold L during the pre-race countdown. Release L and hold R when the countdown reaches "3". Release R and hold L when the countdown reaches "2". Release L and hold R when the countdown reaches "1". If done correctly, your boat will get a faster start and a four-second boost.
All Tracks in Two-Player Mode
Play each race in two player mode and win to unlock secret tracks (for two player only). Eventually, you'll unlock all the tracks and then all the secret boats.
This unlimited two player mode is great for practicing and finding shortcuts.
New Tracks and Boats
To race the medium tracks, finish each of the three Easy courses in the Top 3 positions, and you will get all the medium tracks, plus medium hydroboats, too.
To race the hard tracks, finish each of the Medium tracks in first or second position, and you will get access to the hard tracks, plus hard boats too.
To get bonus tracks, finish each of the Hard courses in first place only, and you will get one bonus track, and bonus cars too. Then, finish the bonus track in first to get another, then repeat that to get the others until you've conquered Hydro Thunder.
Race as a Fishing Boat
Enable all of the hidden tracks. Highlight the Thresher at the boat selection screen. Then, hold L + R and press View two times. Select the Chumdinger to race in a fishing boat.
Race as the Tiny Titanic
You have to beat the easy courses in the top three to get the medium courses. After you have the medium courses then beat them by placing in the top two to get the hard courses. Beat these by placing first in all the races to get the bonus tracks. Beat the first three bonus tracks in first and you will be able to race with the most awesome boat in the game. The Tiny Titanic.
Turbo Start With +4 Boost
Hold reverse throttle when the countdown begins, and just as the "1" is about to disappear, press and hold the accelerator