Custom (Submarine-Like) Character Move System?

[ahmettrPro2]

@Infinite_Visions

		local bodyForce = Instance.new("BodyForce")
		bodyForce.Parent = game.Players.LocalPlayer.Character.HumanoidRootPart
		bodyForce.Name = "Forward"

You should set the parent after naming the BodyForce to use up less resources.
Remember, always set the parent last.