Reaching the High Charity conduit
From Halopedia, the Halo wiki
There is a way to get to the start of the conduit on the final section of the level High Charity. If you get the Sputnik Skull, you can grenade jump to a safe spot.
To do this, you need a grenade and the Sputnik skull. When the last stage of the level (Once More With Feeling) begins, go to the right and to the edge of the platform. Bellow is a place that you will die if you fall. But, if you grenade jump as far as you can to the right, if done correctly, you will land higher up, and won't die. The reason is that the point where you die is lower, but you have ended up higher on the ground. Now walk along to the conduit, without going low. You can reach the other end of the conduit.