Arguably the most visually stunning Devil’s Bath is located within the near Rotorua, on New Zealand’s North Island. Wai-O-Tapu is a Māori phrase meaning “sacred waters,” and the entire region is part of the Taupo Volcanic Zone, an active geothermal area for over 2 million years.

The phrase (historically recorded in German as Des Teufels Bad ) is a poignant historical term used in early modern Europe to describe severe, paralyzing depression and religious melancholy . For centuries, those trapped in the profound darkness of what we now diagnose as clinical depression were believed to be swimming in the murky, suffocating waters of the Devil’s own bath.

This dark chapter of history was unearthed by UC Davis historian , who discovered hundreds of such cases. Her research became the foundation for The Devil's Bath , a film by Austrian directing duo Veronika Franz and Severin Fiala, known for their psychological horror films Goodnight Mommy and The Lodge .

The unusual hue is caused by deposits of sulphur and ferrous (iron) salts that rise to the surface and reflect light. The water is highly acidic, with a pH of approximately 2, and emits a pungent "rotten egg" smell due to hydrogen sulphide gases.

According to the religious doctrine of the time, committing suicide was an unforgivable sin. Those who took their own lives were denied a Christian burial and doomed to eternal damnation in hell, with no opportunity for confession or absolution. Caught in the grip of severe depression and desperation, primarily women saw no way out of their misery. To escape hellfire, they devised a terrible loophole.

The Devil’s Bath: Exploring New Zealand’s Surreal Acidic Wonderland

The film's most chilling element is its historical accuracy regarding a phenomenon known as suicide by proxy The Theological Loophole

There is a historic swimming hole and rock formation known as the Devil’s Bathing Hole, often associated with local folklore and ghost stories from the early settler colonial era. Hells Canyon, Idaho/Oregon

Unlike many modern horror films that rely on quick pacing, The Devil's Bath takes a slow-burn, almost documentary-like approach, emphasizing the grueling monotony of daily life in the 1750s.

Bright, direct sunlight causes the yellow sulfur particles suspended in the water to reflect brilliantly, creating a glowing chartreuse or lime-green color. On overcast days, the water may look like a deeper, murky olive green.

The opening sequence immediately establishes the film’s grim, unflinching tone. A middle-aged woman holds a baby at the mouth of a towering waterfall. Without a flicker of emotion on her face, she tosses the child over the edge. The infant plummets out of sight. The woman then walks through dense, spectral mist to the local authorities and declares, “I’ve committed a crime.” She is later beheaded, her severed head locked in an iron cage beside her decaying corpse—a grotesque warning displayed publicly in the forest for all to witness.

Despite the danger, The Devil’s Bath remains a top tourist destination. Visitors marvel at the stark contrast between the lush New Zealand forest and this glowing, steam-shrouded pit of acid. It serves as a stark reminder that nature’s beauty is often a mask for extreme peril.

“The Devil‘s Bath” is a phrase of extraordinary range. It can be the title of a devastatingly powerful 2024 Austrian film about depression, religious extremism, and the hidden history of “suicide by proxy.” It can be the 18th-century vernacular for the blackest, most suicidal melancholia. It can be a neon-green sulfur pool in New Zealand, a translucent swimming hole in Virginia, or a dark cenote in Canada. It can even evoke a cruel medieval punishment.