The Harbor is hardly the safest place in the city, to say the least. The place has seen all sort of illicit cargo, and all sort of illegal dumps. It's only sort of a joke that it's a stretch to call the water here 'water' anymore. Bruce has tried to fund clean-up efforts, of course, but... well, there's always a new round of Fear Toxin or Venom or chemical waste or something getting dumped in. It's an uphill battle to get it anything resembling 'clean' again.

Of course, all of that is just added problems to the base fact of air-breathing organisms that, if you fall into the water, and don't get back to the surface fast enough, you'll drown, plain and simple. So when the explosion meant to shake the two of you off your pursuit of tonight's mission targets knocked you into the Harbor water, and you didn't resurface immediately, Bruce had more than one reason to be a bit panicked by that.

So of course he abandoned the chase to throw on his rebreather and leap in after you. It wasn't even a choice. Making sure you make it home safe is far more important than catching the criminals, at the end of the day. He's not sure if the explosion hurt you, or the long fall into the water, or if you were just too dazed by all of the above to be much of a strong swimmer in the moment; it doesn't matter in the end. He spots you, swims to you as fast as he can, and lugs you along up out of the murky, polluted water and back to shore, praying you're alright.