All codes are entered at the main menu:
All Boards
Press Up x2, Left x2, Right x2, Down x2, Up, Left, Right, Down, Up, left, Right, Down.
The message "You got all the boards... Or did you?" will come up if you did it right.
All Levels
Press Square x4, Circle x4, Triangle x4, Square, Circle, Triangle. The message "Travel Visa Approved" will come up if you did it right.
Clear All Gaps
Press the combo of (R1, L1, L2, R2) x4.
The message "Wakeboarding Royalty" will come up if you did it right.
Play as Jordan
Make a perfect run during all the Star Search challenges (collect every possible star) to unlock Jordan, the second hidden character.
Play as Summer
Complete the game with any character and finish the credits level to unlock this bikini clad wakeboarder.