Critical Depth Codes -

Invincibility:
Quickly press L1, R1, L1, R1, Up, Down, Left, Right during game play. A sounds will confirm correct code entry.

Unlimited weapons:
Quickly press L1, R1, L1, R1, Up, Down, Left, Down during game play. A sounds will confirm correct code entry.

Drop pod:
Quickly press L1, R1, L1, R1, Up, Down, Left, Up during game play to force opponents to drop their pods. A sound will confirm correct code entry.

Quadruple weapon damage:
Quickly press R1, R2, R1, R2, Up, Down, Up, Down during game play. A sounds will confirm correct code entry.

Stun blast:
Hold R2 and press Right, Left, Up. Note: This assumes the controller is in the default configuration.

Depth charge:
Hold R2 and press Left, Right, Up. Note: This assumes the controller is in the default configuration.

Lay a mine:
Hold R2 and press Right, Left, Down. Note: This assumes the controller is in the default configuration.

Surface mine:
Hold R2 and press Left, Right, Down. Note: This assumes the controller is in the default configuration.

Mr. Phatt submarine:
Complete the game under the medium difficulty level. Defeat Mr. Phatt using a combo attack that results in a minimum of 48 points of damage.

Agent 326 submarine:
Complete the game as Mr. Phatt under the "Captain" difficulty level. Defeat the Cephalopods (Bosses) with a final score over 1 million points.

Abbadon submarine:
Complete the game as Agent 326 under the "Captain" difficulty level.

Overseer submarine:
Complete the game with each of the regular characters under the "Captain" difficulty level. Note: Save the game each time the game is completed.