Watercraeft (or watercræft) is the ability of the vodyanoi to mould water into shapes.

"You'll see the dockers doing it sometimes, in Kelltree or Smog Bend. A whole gang of them can shape quite a bit of the river. They dig holes in the water down to where spilt cargoes lie on the bottom, so the cranes can hook them. Fucking amazing. In rural communities they use it to cut trenches of air through rivers, then drive fish into them. They just fly out of the flat side of the river and flop onto the ground. Brilliant. ... Anyway, these days it's mostly just used to arse about, make little sculptures. They have little competitions and whatnot."

(Isaac talking to Yagharek)