There’s nothing subtle about the Wang Saen Suk Monastery garden, 90 minutes drive south of Bangkok, apart from its location, hidden down a quiet lane not far from the coastal resort of Bang Saen. At the entrance, a brightly coloured sign proclaims “Welcome To Hell”, while beyond lies a garish, in-your-face morality tale of sawn torsos, boiling vats and devilish figures tormenting worldly sinners.

The Wat (temple) Wang Saen Suk Hell Garden is a sort of unsavoury Buddhist theme park with a message. Judgement is black and white; punishments are swift, painful and gory.

I wondered how I would be judged as I tossed 20 Thai baht (30p) into the cavernous belly of a fat Buddha – a collecting box – and followed a Thai family with two young boys aged six or seven into the Devil’s lair.

Most Buddhist temples and monastery gardens have some reference to the nether world – modest frescoes on the inner wall or gilded friezes of Buddhist hell – but few go as far as Wat Wang Saen Suk, whose monks created their vision of hell as an elaborate, shock-horror sculpture garden some 20 years ago.

The centrepiece of the garden is a pair of giant Earthly sinners; an emaciated male with protruding ribs and long drooping tongue, and a frightful looking female with ugly sagging breasts and a swollen belly.

It’s not clear what their sins were, but an adjacent sign suggests: “if you meet the Devil in this life don’t postpone merit-making which will help you to defeat him in the next life. Donate a little each day and you’ll have a happy life.” I only hoped my 20 baht would do the trick.

Around the giant sinners stand a further 21 life-size sinners, whose heads have been turned into various animals according to their misdeeds. Thieves are transformed into monkeys; the dishonest into toads; the corrupt into pigs.

Many ideas are familiar enough to visitors with non-Buddhist backgrounds, although there are some specifically Asian references. Those who steal others’ cooked rice, for instance, are transformed into cartoon-like birds. Some transformations, however, are simply a mystery to me. Why should arsonists be turned into snakes? Or hooligans into crocodiles?

Ecology or environmentalism figure high on the monks’ list of priorities. Those who “destroy plants or herbs useful to humans” are turned into goats – which, unfortunately, probably makes them even more efficient at destroying vegetation. Those who steal “aquatic animals” become fishes. While, for some unspecified reason, “ones who destroy the wilderness” appear twice, once being transformed into elephants, later on into deer.

The young Thai brothers were having a good laugh at the comical transformations, some of which looked like second-rate sci-fi movie characters beamed down to help save the Earth from the Devil himself. Their laughter, however, turned to cries of horror as they moved on to the first of a series of lurid scenes representing the five Buddhist precepts supposed to be followed by lay people, an equivalent of Christianity’s Ten Commandments.

Humans who violate the first principle – thou shall not kill – are shown having their innards ripped out by birds, being speared to death by devilish-looking rogues, and as humans with pig faces being hacked to death with machetes. And the horror continues, with warnings of just what awaits those who cheat, steal, commit adultery, or get hooked on gambling, drugs or alcohol.

The sculptures, a form of popular folk art, are comparable to mediæval morality paintings in the Western tradition: a larger than life, three-dimensional equivalent, perhaps, of Hieronymous Bosch’s terrifying visions of hell. Bosch was preoccupied with sin and eternal damnation, notably in paintings such as ‘The Seven Deadly Sins’ or ‘The Garden of Earthly Delights’, the latter painted around 1505–10 and depicting a nightmare vision of the origin and punishment of sin.

In a similar vein, the Wat Wang Saen Suk Hell Garden represents a Buddhist iconography of hell and the underworld. It’s apparently no place for liberalism: while one image depicts a specific penalty for a woman who kills her husband, there is no equivalent for a man who kills his wife. Another particularly gruesome sculpture shows a woman being squeezed in a giant vice for practising birth control or having had an abortion.

Most images, however, are more typical portrayals of sin, salvation and judgement. In one scene, a surprisingly young couple, held in chains by one of Buddha’s disciples, kneel before the ‘death king’, Phya Yom. Their hands are held together in prayer, or pleading, while Phya Yom decides their fate.

To Phya Yom’s left, a clerk holds a golden ledger in which he enters the human’s good Earthly deeds. A clerk on his right inscribes their sins on a ledger made of dog skin. After careful investigation, the death king decides the humans’ fate, sending them to heaven or to hell – which in Buddhism comprises 136 different fiery pits. One special pit, icy cold and pitch dark, is reserved for those who have hurt monks or their parents.

The Wat Wang Saen Suk is by far the largest hell garden in Thailand. However, near the ancient city of Sukhothai, in northern Thailand, a more modest hell garden predates Wat Wang Saen Suk by more than a decade. Here, in 1973, a monk with a taste for folk art, Phra Sumroeng, created an eccentric monastic centre at Wat Thawet.

As at Wat Wang Saen Suk, Wat Thawet’s sinners are depicted with animal heads and alcoholics have burning liquids poured down their throats. A woman who has had an abortion, rather than being grotesquely tortured, is here shown carrying a giant devouring worm.

Although often gruesome, Thailand’s hell gardens are popular weekend destinations for family days out. As well as an entertaining way of teaching strict morality, they also encourage donations as a form of merit-making to support the monks and the monasteries.

A carefully positioned sign at Wat Wang Saen Suk both tugs at your conscience and plays on your fear of the unknown. “The person who has bad luck”, it says, ”should get rid of it by donating. The donation should be equal to the number of the year that you were born plus your age at one baht for each year.