Critical Depth Cheats

Surface Mine

Hold R2 and press Right, Left, Down.

Invincibility

While playing press L1, R1, L1, R1, Up, Down, Left, Right.

Infinite Weapons

While playing press L1, R1, L1, R1, Up, Down, Left, Down.

Guided Missiles

Press and hold TRIANGLE, then press R1+L1 simultaneously to fire a guided missile. You can now direct it with the d-pad or detonate the missile at any time by pressing R1 and L1.

Quad Damage

To do four times the normal damage, press R1, R2, R1, R2, Up, Down, Up, Down while playing.