Full pause screen:
Press Start to pause game play, then press X + Y.

Active map:
Hold X (sonar) during game play for a long time. Press X again to return to normal.

Glitch: Swim outside the game world:
Encounter the Boss in the "Blades..." level. It is a large room with a Boss that resembles a large dragonfly larvae. Go to the bottom of the room where you can refill you air supply with the bubbles coming out of the ground. Next to the bubbles on the floor near the wall is a small hole. Go through it and get outside the game world.