You can fly! Go to the edge of any swimable water and use horn dive. Try and make sure you are in between the land and water (sometimes when you standing on nothing and land). It takes a while but it's worth it! The glitch allows you to swim - in air! You can pass through anything - even the landscape. To exit just jump back into some water. Be careful though - this cheat confuses the game so if you go too high or too low you might have to reset your PS2 because it doesn't allow you to go up or down!