In Buddhism, Avīci (Sanskrit and Pali "without waves," also transliterated Avichi, Japanese and Chinese 無間地獄, むげんじごく and 阿鼻地獄, あびじごく) is the lowest level of the Nirayas, Naraka, or "hell" realms into which the grave karma of living beings leads in the cycle of rebirth.
It has been described as being a massive cube 20,000 yojanas side to side, buried deep underneath the Earth. Beings -- whether from heavenly, human, animal, or other realms may come to be reborn -- in Avīci may have come to be there as a karmic result of heinous acts known as the Five Grave Offenses:
- Intentionally murdering one's father
- Intentionally murdering one's mother
- Killing an arhat (enlightened being)
- Shedding the blood of a buddha (silent or teaching)
- Creating a schism in the monastic Sangha.
Buddhism teaches that rebirth into Naraka, like every other form of rebirth, is impermanent. After a long time, with suffering exponentially worse than what led there, the karma keeping one there is exhausted. Then it is possible that one goes on to be reborn elsewhere. (However, sadly, the tendencies that led to such karma and such a result of karma are usually not healed by torment; so one may again commit an act and end up right back such that it feels like one can never escape).
The suffering in the Waveless Deep is the longest of all the miserable levels of hell, by some accounts over 1018 years long. Some sutras state that rebirth lasts innumerable aeons (kalpas). When the denizen passes away after one aeon, he or she may again be reborn in the same place, undergoing suffering for another aeon, and so on until exhausting the heinous karma. For this reason, this hell is also known as the "non-stop way" (無間道).
Nichiren, the founder of "Nam myoho renge kyo" chanting form of Buddhism, famously wrote that Buddhist monks who ignore the passages in the Lotus Sutra, which Mahayana claims is superior to all other sutras would fall into the Waveless Deep.[Ref.] Except for Nichiren, it is extremely rare for a Buddhist monastic to condemn anyone to hell. Although the Lotus Sutra itself states, "When one's [those who slander] life comes to an end, one will enter the Avichi Hell."
Rebirth there or any lower realm for that matter can be seen as a process of purification. It is very misleading to see it as a form of "punishment." Impersonal processes of mind and karma (by impersonal "laws" known as niyamas) govern the process. But a supernatural being called Yama is often cited as being the King of the Dead, of death, of the underworld, or hell. (Niyāma = Yama?)
To personalize (and make comprehensible what is impersonal and difficult to comprehend) stories are often told of being "judged" by Yama, the King of the Dead, to determine our future. These stories may be experienced as literal or understood as quite metaphorical: From the Buddha's time the story was that one would be asked a series of questions about whether or not one had seen the "signs."
"'Signs'? What 'signs'?" one will ask. Old age, sickness, death, ignominy -- did one never see them? Yes one saw them. Did one never think they applied to everyone alike, including oneself? "Uh, uh," one will say for not having led a contemplative life, an "examined" life as Socrates would say, a mindful life well aware of death, rebirth, karma, and the terrible dangers of greed, aversion/fear, and delusion.
A later story, more popular in some Buddhist countries, was that Yama would ask one to walk a fine rope with heaven at the end of it and hell in a chasm below. Since the weight of skillful karma is so light and unskillful karma so heavy, any weighty karma will break the fine line and drop one into misery.
Who governs our fate, Yama after death or we ourselves during life? Will is karma -- the seeds with the potential to ripen -- or what we have willed, performed, and accumulated. We are responsible for that. Everyone is the heir of his or her own actions when they bear their fruits (phala) and mental resultants (vipaka). Karma will accompany us, and the pleasant and unpleasant consequences of karma, the results, will meet us when and if they get the opportunity.
For "beings are owners of karma, heirs of karma, born of karma, related through karma, and have karma as their arbitrator [judge]. Karma is what distinguishes beings in terms of coarse and fine" (MN 135).
Rebirth in Avīci is the unfortunate result of one's unskillful, in many cases dreadful, deeds and never really the decision of a judgmental God or malevolent deity like Yama.