Somehow the bee had fallen upside down into a shallow patch of water. It was trying to get up, but to no avail.
I got a piece of cardboard and carefully lifted the bee out. I put it out on the balcony, where it could let its wings dry.
If that didn't work, I would put it out of its misery. But it was worth trying.
I checked several times. It was still there, still wet. And then, it was gone. Godspeed, bee!
All for selfish reasons: I love honey.