Super Bouncing

Summary
There are many crouching glitches in Halo 2. In some levels, there are areas that you can get into that are low enough for Master Chief to duck under and let go of crouch and still be crouched. If you are crouched, you can continue to walk; it will show you in the same place walking into the wall. But if someone else watches you, they will see you walk through the wall or in some cases a root. This can be used to your advantage, allowing you to reach top parts of levels that are not possible to get to. They call these bounces or super jumps.

Warlock
Duck under the root in the blue base, and start to walk pointing a little to your left. Soon you will be free of the root. You can only turn yourself with the look thumbstick, go forward until you see the area between the air chute and a little wall in front of the base. Jump, do not hit the other level as you jump. Remember you can only turn, hold in forward all the time. If you do this correctly you can send yourself flying to the top of the level.

There are many other's in levels such as Zanzibar, Coagulation and others.

On Zanzibar go into the big building (the only building)Go to the hall with the closable shutters.There are 2 glass windows with a battle rifle inbetween them.Break the window closest to the wheel.Crouch under the piece of glass and let go of crouch.You should automatically stay crouching.Hold forward till the pillar shakes and hit jump.You will end up on top of the base.

Zanzibar (multiplayer)
On this level there are many known superjumps. The first is inside the defensive base, on the 2nd level near the gate opener. There are two windows facing inside, break the 2nd one out completly. (the one closest towards the beach). There will be a shard left on the beach side, crouch under the shard. Once the screen begins to shake, jump and keep pressing A. When you hit the ground, you should superjump to the top of the base. To do this one, I think of the shard of glass as a central vertical plane, and if are angled to the left more (facing away form the center) it makes it easier when you jump off, you don't want to land very far from the wall, and if you hit the wall or column on your jump it messes it up and you won't super jump

The 2nd is near the defensive base, right outside of the gate that opens up. This might be hard to understand, but there is a corner made from the rock wall and a rock piece that is jutting out. Crouch there, and then run up over the rocks near the corner of the level,and land on the cement that is stained with blood, or rust. You should bounce up unto a ledge on the side of the level.

The 3rd is similar to the previous one (#2). Go to the fan in the center of the level. On the right side of the fan (looking from the defensive base toward the beach), stand on the concrete and there is an angled part of the fan that you can crouch into. Then, move back, and jump on the corner of the lower part of the concrete (one side is slanted and then flattens out) when you hit the edge it should bounce you up to the top of the fan.

The 4th is on the beach staircase(the smaller one). Get on the rail of it and walk to the top. Crouch there below the rock and walk out. Then run up it until you see a bit of a divit in the rail. Jump over that spot and and land on the highest part before the break in the larger staircase. If done right, you should be on the top of the rock cliff between the beach and the sniper spawn by the wheel.

Turf
On Turf, theres a fun trick if you edit the game type to allow full overshields and rocket launchers. Then find the black shields that are around the medic hut. If you stand on the support that is on the ground, and shoot a rocket launcher into the top part of the shield, it will launch you straight into the air like a superjump. This also works on Relic.

The sheild catapult can also be done with the wings of a banshee, but this is only for experienced glitchhunters.

Explanation
No one knows how these work, but the major theory is this: When you land on a line, you sink through the level a bit. The game realises this and pushes you back out a bit. When you go into a crouch spot, the game confuses you with being a part of the level. Then, when you land on the line, you sink through further. Sometimes, this makes you bounce higher, but occasionally you will fall through the level and be killed by the "guardians." This is the game's way of saying "I screwed up and killed you, so I won't punish you for my mistakes."

It may also be a left over from the game's designers to take pictures of a level from an elevated perspective.