According to traditional scholastic Buddhist texts, there are at least 144 hells. Although stay in none of those hells is literally eternal, it is nevertheless incredibly long and the broad range of tortures stretches sadistic imagination beyond the extreme. Given that compassion plays a central role in Mahāyāna Buddhism, some of its scriptures introduce the teaching that Bodhisattvas enter the various hells in order to transform them into rather pleasant places and liberate their inmates from their horrendous pain. The paper explores how Bodhisattvas can do that and speculates what this might imply for a renewed Buddhist concept of hell.