If they were going to die anyway, Harry decided that right before the water reached neck level, he was going to strangle Nott. It would make him feel better about dying.
His lips tightened and he crossed his arms over his chest. "If you think that will work any better than the Alohomora, then go right ahead," he told Theo sourly. Spells had seemed to bounce right off, but it was worth a try.
He'd have thought of that, eventually. Or so Harry told himself.