Tsunami Zone
Looking for some really huge waves? Don't worry, we've got you covered. Here's how to find a nice little secret spot that's all about big waves. To get there, select Free Roam from the main menu. Now pick a racer with a high top speed (remember that you can increase the top speed by customizing your rider by pressing Z). Go to Dolphin Park. Look straight ahead and slightly to the left. See that island in the distance? Right in front of that island, you will notice a circle of red buoys. The trick is to get into the circle of buoys by leaving the course -- before the five second Time Out clock runs out. Your best bet is to turbo as you leave the course, do a trick to help fill up your turbo meter while you're boosting, then hit your boost again. If you've done everything right, the timer will disappear and you will find yourself in your very own Tsunami playground. The waves here are big enough for you to do tricks off them, so have fun jumping!

Fast Recovery
Here's another little undocumented feature... Don't just sit there when you fall off your jet-ski. Tap the A-Button repeatedly to get back on your ride in no time.

Load Screen Fun
Whenever a new track loads (on the screen displaying the track name), try moving around the analog stick: you can stir the water and cause ripples while you wait.

Ride a Dolphin
Oh yeah, baby. Want a chance to ride a dolphin instead of a jet ski? Go to the password menu and enter this code: DLPHNMOD. Now you'll be able to pilot a porpoise in the game's Free Roam mode, complete with classic Wave Race 64 music. Happy flippin!

Soft Reset
To perform a soft reset without getting up and hitting the reset button, press B, X and Start at the same time and hold them for two seconds.

Start Screen Fun
Here's another classic Nintendo easter egg: wait till the START logo pops up on the game's title screen. Now move your left analog stick. You can move the Start logo across the screen and cause ripples.

Turbo Start
Here's a classic Nintendo trick: to start off a race with a full turbo meter, hit the accelerator right when the starting lights turn green. If you do it right, you will have full turbo right away.

Turn on Password Mode
To get to the Password screen, go to the Options menu and hold X, Z and START. Now you'll be able to enter all sorts of cheats as well as passwords to participate in official Nintendo tournaments.

Unlock All Weather Conditions at Once
To unlock all the weather conditions in the Time Trial Mode (without having to race each track on each condition), including the rare Storm condition, you have to complete the Expert Championship.
Third Place: Unlock all Time Trial Weather Conditions for Normal
Second Place: Unlock all Time Trial Weather Conditions for Hard
First Place: Unlock all Time Trial Weather Conditions for Expert

Unlock Trial Mode
Enter the training mode and complete all training objectives on the Beginner and Master settings. Simply follow the directions and complete the tricks (you need check marks next to every trick or control option, even the painfully obvious ones like "go straight" and "turn." Once you have finished them all, a new option called "Trial" is available under Training. It's a stunt variation of Dolphin Park.

Unlock the Secret Tracks
To unlock Blue Storm's three secret tracks, you have to play through the Championship Mode on all three difficulty settings.
The following tracks can be unlocked:

Arctic Bay: Beat Championship on Normal
La Razza Canal: Beat Championship on Hard
Strongwater Keep: Beat Championship on Expert

Tournament Passwords
Like many Nintendo games, Blue Storm has a tournament password option built in. These passcodes let you race a Time Trial or Stunt track, then tally your totals and spit out a code that you can use to enter and get ranked in Nintendo-held tournaments. You can also use some of these codes to play a level you may not yet have unlocked (slacker!).
To enter a password, go to the Options menu, press X, Z, and Start, then select the Password entry option.

Passwords:

KTUPWNPD: Dolphin Park Stunt Track
WCX5WP5A: Southern Island Stunt Track
J784WMHF: Lost Temple Lagoon (Normal) Time Trial
LQ3TRKTE: Lost Temple Lagoon (Hard) Time Trial

How to Unlock Time Trial Weather Conditions
To unlock the different weather conditions in the Time Trial mode, you need to play the Championship Mode... a lot. Every time you enter a new Championship, the weather conditions for the tournament days are randomized. If you complete a race on a track, the weather condition that you encountered will be unlocked Time (only for that difficulty level and track). So if you want to unlock Southern Island with rainy weather, check your forecast. If rain is predicted for the third day, choose Southern Island as your third track to race.