When turning big wheels, as when shutting off the water, turn from the farthest point to go faster.

Two-player mode (PAL and Japanese NTSC versions)
Successfully complete the game and wait for the credits to end. Once you regain control of Ico, look for Yorda near the seashore. A save prompt will appear after the final ending. Save the game and restart to have Yorda playable using controller two and new music.