Sometimes a drowned man returns as a monster, to haunt the living. Tormented with his death, he murders his victims. He prefers to draw them beneath the water's surface, tearing the drowning victim to shreds with sharp claws, and eat them like a wet biscuit. Such creature is called a drowner. They are quite often found at the banks of the Pontar, since the huge river with regular shipping and riverside villages provides them with ample sustenance.
"When monsters are really crappy, ganging up makes them happy". Drowners are not the mightiest beasts in the world, so they hunt in groups, in accordance with the above saying. They are surprisingly fast on land, but are a threat only to fishermen and washerwomen. They can best a witcher only if he is drunk or in love. Sometimes, however, a more robust specimen is found among the drowners. It is called a drowned dead and can command the entire band. Thus it's best to eliminate it first.
One could say that if drowners chatted among themselves, Geralt would be highly esteemed among them after his exploits in Vizima. Yet drowners do not chat - they are dumb like a left shoe. And good. Fast style should be used when fighting them, and one must spin swiftly before they flee from a witcher's blade. Enough said.
As they are already dead, drowners do not fear poisons, and even a large loss of blood makes no impression on them. This ends the list of the monsters' strong points, however, as the rest of the witchers' arsenal is extremely effective against them. Thus the drowners can be killed with fire, immobilized by traps, knocked down and, above all else, sliced and diced until slime spills from their ears.