Wow, yes! If he thought Harry was going to drown, Snape would have run, shedding his clothing, to get him out of the pool, and then perhaps, spanked him for being an idiot--I can't believe you figured out a scenario in canon when they could have ended up naked together this way! Now I'm going to have more enjoyment staring at Harry's adorable naked tushie and Snape's beautiful feet, and enjoying what my computer screen can show me of the way you colored this--it looks great!