Hold L + R and enter the following:

Bottomless canteen: LEFT, B, X, DOWN, B, A, B, X
Original Pitfall: X, X, LEFT, RIGHT, X, B, A, UP, X
Hyper Punch Mode: LEFT, RIGHT, X, UP, X, RIGHT, LEFT
Play as Nicole: LEFT, UP, DOWN, UP, X, UP, UP

Pitfall II  -  Collect and use all Idols.

Classic Pitfall 2 - Lost Caverns mini-game - Hold L + R and press Left, Right, Left, Right, Y, Y, Y, at the title screen. The "Lost Caverns" option will be unlocked at the "New Game/Load Game" screen. Alternately, buy all items from the Shamans and collect all Idols.

Play as Retro Harry - Hold L + R and press Y, Left, Down, B, X, Y, Y, Left at the title screen.

Defeating the Demon Jaguar - If he enters into a rage (running, leaping at you non-stop, giving you no chance), keep on super running either left or right until he finally stops. When he does, kick him very quickly. Repeat this process to destroy him. This works about every four or five times. If it does not
work, start running behind him in circles when he runs in circles. Try to cut him off and kick him.

Defeating Pusca's minions - Instead of hitting or kicking the pillars towards them, you can get your pick axes out and spin around by pressing Down then repeatedly pressing C-stick Up. Note - You are invincible when doing this, but you still need to be careful when Harry becomes dizzy. Quickly press A to stop being dizzy and start spinning again before they resume shooting at you.

Defeating the Mouth Of Inti Boss - Use the Fountain if required. Walk over to the edge of the cliffs.

Entering the Monkey Temple level - On each of the opposite ends of the closed door, there is a picture of a monkey inside a ring of fire. Light the bowls in front of the pictures to enter the Monkey Temple.

Getting past the Plane Cockpit level - Swing on the first vine then to the next one. When you are swinging on the second vine, look ahead for an opening on top of the plane. Jump onto the top of the plane, roll, and sweep kick the glass. Then, continue rolling in. After the scene, jump kick the cracked glass in front of you to continue to the Native Jungle.

The explorer at the Flooded Courtyard - When you have received your pick axes, go through the Jungle Trail until you reach the hole that leads to the Flooded Courtyard. Go around it to the mesh of roots, and roll under it by holding down R and using the C-stick to control your movement. Get past the scorpions and use your pick axes to climb up the ice. On the ledge above the ice, you will see a hole, in which is the shortcut to the Flooded Courtyard. Roll under it. When you arrive at the Flooded Courtyard, to your right you will see the explorer in a cage. On the bottom ledge there is an idol.
Sent in by Grandville

Original Pitfall 2: Lost Caverns game - At the title screen, hold L + R and press Left, Right, Left, Right, Y(3). If you entered the code correctly, a message will appear. The "Lost Caverns" option will be unlocked at the "New Game/Load Game" screen. Alternately, buy all items from the Shamans and collect all Idols.

Entering the Monkey Temple level - On each of the opposite ends of the closed door, there is a picture of a monkey inside a ring of fire. Light the bowls in front of the pictures to enter the Monkey Temple.

Getting past the Plane Cockpit level - Swing on the first vine then to the next one. When you are swinging on the second vine, look ahead for an opening on top of the plane. Jump onto the top of the plane, roll, and sweep kick the glass. Then, continue rolling in. After the scene, jump kick the cracked glass in front of you to continue to the Native Jungle.

The explorer at the Flooded Courtyard - When you have received your pick axes, go through the Jungle Trail until you reach the hole that leads to the Flooded Courtyard. Go around it to the mesh of roots, and roll under it by holding down R and using the C-stick to control your movement. Get past the scorpions and use your pick axes to climb up the ice. On the ledge above the ice, you will see a hole, in which is the shortcut to the Flooded Courtyard. Roll under it. When you arrive at the Flooded Courtyard, to your right you will see the explorer in a cage. On the bottom ledge there is an idol.