7.
John nodded. Sherlock pulled the trigger.
A wall of solid sound turned the world white. John was no stranger to explosions, but there was no getting used to the way world ripped apart, leaving him momentarily blind and deaf and senseless while the floor became the ceiling became the wall became the floor. He rolled, had started rolling even as Sherlock made a move with the trigger, and when everything settled he had forgotten how to feel. He didn't think he was shot. But he felt no pain at all, and that couldn't be right, either.
He moved even before he allowed his senses to take back in the world, on his feet and looking before he remembered what he was looking for. What he saw was a blast radius, far too small and compact for what the bomb had looked to be carrying. If he had been wearing it, it would have been enough. He didn't see Moriarty anymore, which was a pity, because in the dazed state the man should have been in, he would have made an easy target to the pent up anger, humiliation, and fear that had been coursing through his veins for the last hour, ever since he awoke and realized both that he wasn't going to make his date and that Sherlock was in danger.
He didn't see Sherlock either. Until he looked in the pool.