The last time, I noticed something was weird, whipped out the ol' zapping, and managed to knock a jolly heck of a lot of doors out of invisibility. Trying to avoid that this time, because it got the things' attention way too quick.

[Rousing it is the last thing he wants to do. Instead, he crouches down, looking for oddities in the water.]

Look for distortions, weirdness. That sort of stuff.