I finally made it to the Shanghai Aquarium. It's a pretty good aquarium, with a decent-sized underwater tunnel, lots of sharks and a decent diversity of other creatures, good signs, etc. But it turned out to also be an excellent place to observe non-aquatic creatures -- in this case, Chinese tour groups.
My second Shanghai sightseeing partner, Matt, and I were taking our time ambling through the first floor of exhibits and had just reached a large, open circular area with big ground-to-waist-height tanks (like the one in the picture at bottom) along half the perimeter. Matt had apparently just been about to comment on how he hoped the aquarium saw enough business to stay afloat, as through two special exhibit rooms we'd seen only a couple handfuls of other people (which was fine by me, since it obviated the need to jockey for space when reading the signs). Before he could vocalize this, though, there was a sudden clamor from the direction of the entrance escalators. Like a train, you can usually hear a Chinese tour group coming before you see it.
Within a few seconds, we found ourselves in the middle of a river of (possibly overseas-) Chinese tourists. The leader was a short woman holding the obligatory tour-group flag (this is common to most Asian tours, in my experience -- the group leader holds the flag aloft so that everyone can look up for the brightly colored piece of cloth rather than crane about for the top of someone's head) and squawking rapidly, only she wasn't so much leading as standing near the top of the escalators and barking out something I couldn't understand.
This was okay because the tour members -- all distinguishable by the matching red baseball caps they sported -- didn't seem to have any interest in being led. The first ones off the escalator strode quickly towards the first tank, and then swiftly around the room, barely stopping, but nonetheless managing to keep up a steady stream of oohing, aahing, and generally excited chatter. I'm pretty sure the first batch of thirty or so had made it completely around the room and had headed off into the rainforest section (at the barking behest of the tour leader, still at her escalator post) before the tail end had even gotten past the entry turnstile.
Matt and I had by now stepped back out of the river and into the center of the room to watch the entertainment. The stream kept coming -- every time there was a small break that we thought might signal the end of the line, another gaggle of red hats emerged into the atrium. The middle and back of the pack contained those sightseers not trying to qualify for the Senior Olympics, but they still moved at a good pace -- a few stopped to pose for pictures in front of some of the tanks, but for the most part it was a line in continual motion. Nobody strayed, nobody skipped around; they just beelined from escalator to first tank, clockwise around the room, and out the door. I would guess that there were at least a hundred people in the tour, and from first to last, with some stragglers scrambling back for pictures at the first tank, they managed to do a complete sweep of the place in less than ten minutes. A very raucous ten minutes, mind you (imagine the sound of indecipherable cocktail chatter, but at 80 decibels). I'm pretty sure they made it through the entire building before we even got to the second floor. At any rate, by the time we moved on to the rainforest area, they were out of hearing range, and we neither saw nor heard them again.

Apart from that adventure, I still can't get over the way aquarium glass only goes up to waist height here. I keep waiting for some American tourist to walk up and stick his or her hand in to try to pet the crocodile/fish/turtle (the shark tanks are in fact fully covered, except for the one where you actually are allowed to pet the animals).