Hydro Thunder

Fishing boat:
Enable all hidden tracks. Highlight the Thresher at the boat selection screen. Then, hold L + R and press Y(2). Select the Chumdinger to race in a fishing boat.

Quick start:
Note: This trick assumes the game is under the default controller setting. Hold L during the pre-race countdown. Release L and press R when the countdown reaches "3". Keep alternating between the two buttons until the race begins. Your boat will get a faster start if the buttons are alternated with the right timing.

Medium difficulty tracks and boats:
Successfully complete all three easy difficulty tracks in first, second, or third place.

Hard difficulty tracks and boats:
Successfully complete all medium difficulty tracks in first or second place.

Bonus tracks and boats:
Successfully complete all medium difficulty tracks in first place to unlock the Nile Adventure bonus track. Successfully complete this track in first place to unlock the next bonus track. A total of four bonus tracks can be unlocked by finishing in first place. All four bonus boats (Fishing Boat, Armed Response, Blowfish, and Tinytanic) will be available after all four bonus tracks are unlocked.