Naraka is a term in Buddhist cosmology usually referred to in English as "hell" or "purgatory". The Narakas of Buddhism are closely related to diyu, the hell in Chinese mythology. A Naraka differs from the hell of Christianity in two respects: firstly, beings are not sent to Naraka as the result of a divine judgment or punishment; and secondly, the length of a being's stay in a Naraka is not eternal, though it is usually incomprehensibly long, from hundreds of millions to sextillions of years. A being is born into a Naraka as a direct result of its accumulated actions and resides there for a finite period of time until that karma has achieved its full result. After its karma is used up, it will be reborn in one of the higher worlds as the result of karma that had not yet ripened. In the Devaduta Sutta, the 130th discourse of Majjhima Nikaya, the Buddha teaches about hell in vivid detail. Physically, Narakas are thought of as a series of cavernous layers which extend below Jambudvīpa into the earth. There are several schemes for enumerating these Narakas and describing their torments. The Abhidharma-kosa is the root text that describes the most common scheme, as the Eight Cold Narakas and Eight Hot Narakas.
Cold Narakas
Arbuda, the "blister" Naraka, is a dark, frozen plain surrounded by icy mountains and continually swept by blizzards. Inhabitants of this world arise fully grown and abide lifelong naked and alone, while the cold raises blisters upon their bodies. The length of life in this Naraka is said to be the time it would take to empty a barrel of sesame seeds if one only took out a single seed every hundred years. Life in this Naraka is 2×1012 years long.
Nirarbuda, the "burst blister" Naraka, is even colder than Arbuda. There, the blisters burst open, leaving the beings' bodies covered with frozen blood and pus. Life in this Naraka is 4×1013 years long.
Aṭaṭa is the "shivering" Naraka. There, beings shiver in the cold, making an sound with their mouths. Life in this Naraka is 8×1014 years long.
Hahava is the "lamentation" Naraka. There, the beings lament in the cold, going haa, haa in pain. Life in this Naraka is 1.6×1016 years long.
Huhuva, the "chattering teeth" Naraka, is where beings shiver as their teeth chatter, making the sound hu, hu. Life in this Naraka is 3.2×1017 years long.
Utpala is the "blue lotus" Naraka. The intense cold there makes the skin turn blue like the colour of an utpala waterlily. Life in this Naraka is 6.4×1018 years long.
Padma, the "lotus" Naraka, has blizzards that crack open frozen skin, leaving one raw and bloody. Life in this Naraka is 1.28×1020 years long.
Mahāpadma is the "great lotus" Naraka. The entire body cracks into pieces and the internal organs are exposed to the cold, also cracking. Life in this Naraka is 2.56×1021 years long.
Each lifetime in these Narakas is twenty times the length of the one before it.
Hot Narakas
Sañjīva, the "reviving" Naraka, has ground made of hot iron heated by an immense fire. Beings in this Naraka appear fully grown, already in a state of fear and misery. As soon as the being begins to fear being harmed by others, their fellows appear and attack each other with iron claws and hell guards appear and attack the being with fiery weapons. As soon as the being experiences an unconsciousness like death, they are suddenly restored to full health and the attacksbegin again. Other tortures experienced in this Naraka include: having molten metal dropped upon them, being sliced into pieces, and suffering from the heat of the iron ground. Life in this Naraka is 1.62×1012 years long. It is said to be 1,000 yojanas beneath Jambudvīpa and 10,000 yojanas in each direction.
Kālasūtra, the "black thread" Naraka, includes the torments of Sañjīva. In addition, black lines are drawn upon the body, which hell guards use as guides to cut the beings with fiery saws and sharp axes. Life in this Naraka is 1.296×1013 years long.
Saṃghāta, the "crushing" Naraka, is surrounded by huge masses of rock that smash together and crush the beings to a bloody jelly. When the rocks move apart again, life is restored to the being and the process starts again. Life in this Naraka is 1.0368×1014 years long.
Raurava, the "screaming" Naraka, is where beings run wildly about, looking for refuge from the burning ground. When they find an apparent shelter, they are locked inside it as it blazes around them, while they scream inside. Life in this Naraka is 8.2944×1014 years long.
Mahāraurava, the "great screaming" Naraka, is similar to Raurava. Punishment here is for people who maintain their own body by hurting others. In this hell, ruru animals known as kravyāda torment them and eat their flesh. Life in this Naraka is 6.63552×1015 years long.
Tapana is the "heating" Naraka, where hell guards impale beings on a fiery spear until flames issue from their noses and mouths. Life in this Naraka is 5.308416×1016 years long.
Pratāpana, the "great heating" Naraka. The tortures here are similar to the Tapana Naraka, but the beings are pierced more bloodily with a trident. Life in this Naraka is 4.2467328×1017 years long. It is also said to last for the length of half an antarakalpa.
Avīci is the "uninterrupted" Naraka. Beings are roasted in an immense blazing oven with terrible suffering. Life in this Naraka is 3.39738624×1018 years long. It is also said to last for the length of an antarakalpa.
Each lifetime in these Narakas is eight times the length of the one before it. Some sources describe five hundred or even hundreds of thousands of different Narakas. The sufferings of the dwellers in Naraka often resemble those of the Pretas, and the two types of being are easily confused. The simplest distinction is that beings in Naraka are confined to their subterranean world, while the Pretas are free to move about. There are also isolated and boundary hells called Pratyeka Narakas and Lokantarikas.
The Dīrghāgama or Longer Āgama-sūtra, was translated to Chinese in 22 fascicles from an Indic original by Buddhayaśas and Zhu Fonian 竺佛念 in 412–13 CE. This literature contains 30 discrete scriptures in four groups. The fourth varga, which pertains to Buddhist cosmology, contains a "Chapter on Hell" within the Scripture of the Account of the World. In this text, the Buddha describes to the sangha each of the hells in great detail, beginning with their physical location and names:
