Unlock Basilisk:
Finish the "Protection Racket" level in captain difficulty.

Unlock Fireshark:
Finish the "Up The Nagau" level in ensign difficulty.

Unlock Guncat Catamaran:
Finish the "Protection Racket" level in ensign difficulty.

Unlock Gunshark:
Finish the "Ships In The Night" level in ensign difficulty.

Unlock Hellcat Catamaran:
Finish the "The Gauntlet" level in ensign difficulty.

Unlock Hydroplane Switchblade:
Finish the "The Gladiator" level in ensign difficulty.

Unlock Jackal:
Finish the "Assault On Black Moon" level in ensign difficulty.

Unlock Lightning:
Finish the "A Friend In Need" level in ensign difficulty.

Unlock Pike:
Finish the "Payment Is due" level in ensign difficulty.

Unlock Salamander:
Finish the "Fish In A Barrel" level in ensign difficulty.

Unlock Tigershark:
Finish the "Sampan Surprise" level in ensign difficulty.

Unlock Switchblade hydroplane:
Finish the "Gladiator" level in ensign difficulty.

Unlock Kingdom Come Battle Mode:
Finish the "Baptism Of Fire" level in ensign difficulty.

Unlock Clanbake Battle Mode:
Finish the "A Poke In The Eye" level in ensign difficulty.

Unlock Metal Massacre Battle Mode:
Finish the "Hurrican Of Fire" level in ensign difficulty.

Unlimited ammunition:
Press Black, White, L, R, click Right Analog-stick(2), press Y, X at the "Start Game" screen, then press Start. 

Unlimited turbo:
Press Up(2), Down(2), Left, Right, Left, Right, B, A at the "Start Game" screen, then press Start. 

Invincibility:
Click Left Analog-stick, click Right Analog-stick, press Down, Left, Down, Left, B, Y at the "Start Game" screen, then press Start. 

All boats:
Press Up, Down, Left, Right, L, B, X(2), click Right Analog-stick at the "Start Game" screen, then press Start. 

All levels:
Press X, Y, Up, Right, Left, Down, Up, Down, click Left Analog-stick, L at the "Start Game" screen, then press Start. 

Blood Ball mode:
Press X, Y, White, Black, B, A, Left, Up, Right, Down at the "Start Game" screen, then press Start. 

Puffer Fish:
Press A, B, Black, White, Y, X, click Right Analog-stick(2), click Left Analog-stick(2) at the "Start Game" screen, then press Start. 

Rubber duck mode:
Click Right Analog-stick, click Left Analog-stick, R, L, Black, White, Up, Down, Left, Right at the "Start Game" screen, then press Start. 

Import boat mode:
Press Y, B, X, A, L, R, Left, Right, click Left Analog-stick, click Right Analog-stick at the "Start Game" screen, then press Start.