Season 2 - nothing too explicit. Two men with bloodied eyes, one frozen to death and one hanged; a woman with a slit throat; a man is strung up and his head held underwater in a drowning attempt; a man is stabbed and pushed off the deck of a ship. Scenes of this type are brief and don't linger on blood and guts.
a woman is kidnapped and chained on season 1.
On season 1, a woman is punched on the face a few times and we see blood on her nose and lips as a result.
Crime scenes on season 2 are very bloody and disturbing.
On season 2, a men is kidnapped, chained and hung upside down above water, in an attempt to be killed by drowning.
Season 3: a men is killed by being nailed to a cross. His tongue is cut out. This is offscreen, but once the detectives arrive to the crime scene, they realize the men is still alive. He loses a lot of blood through his mouth.