Drive a Dinghy
From Halopedia, the Halo wiki
First, the player must get a gun with a large magazine, preferably an SMG. From Forge, the player must then place a dinghy somewhere but not place it in the water yet. They should fill the dinghy with the weapon they chose. They should be set to instantly respawn. They must pick up the dinghy slowly and not spill the weapons in the water and point the engine towards their intended destination. They should quickly get onto the dinghy and shoot/spray 3-4 rounds onto the dinghy. The amount of bullets does not matter. The player should then face the direction of their destination with the engine to their front.
Next, they should melee the engine four times, shoot, then melee again like before, and then shoot it again. They should repeat the cycle until they reach their intended destination. Additionally, the player can place a turret on the back of the dinghy for a friend to operate and kill enemies. To steer the dinghy, they can melee the sides of the engine.