Ecco The Dolphin - Defender Of The Future

Go to the title screen and press the following button combinations:

Select stage:
Hold L1 + L2 + R1 + R2 and press Up, Up, Down, Down, Triangle, X, X.

Get all vitalits and unlock stages
Hold L1 + L2 + R1 + R2 and press X, X, Circle, Circle, X,
Circle, Up, Down, Down

Unlimited health
Hold L1 + L2 + R1 + R2 and press Triangle, X, X, Up, Up, Down.

Unlimited air
Hold L1 + L2 + R1 + R2 and press Square, Square, Triangle, X, Circle.

Swim with a group
Hold L1 + L2 + R1 + R2 and press X, Up, X, Down, X, Triangle.

Unlock Dolphin soccer mini game.
There is a soccer ball on Powers Of Levitation level in the room
where the clan General is located. Pick up, after jump to to the
level selection screen. You will see a Dolphin soccer game option.