Ecco the Dolphin: Defender of the Future (PS2)

Infinite Air
At the title screen hold L1, L2, R1 and R2, and press Up, Up, Down, Down, Triangle, X and Circle to unlock infinite air.

Unlock All Levels
At the title screen hold L1, L2, R1 and R2, and press Up, Up, Down, Down, Triangle, X and X to unlock all levels.