Mysterious 'bottomless' water hole in middle of village has killed many that have tried to explore it

In the French village of Tonnerre, there is a spring which keeps pouring forth plenty of water and has become famous throughout the centuries.

It's called the Fosse Dionne, which roughly means 'divine pit' in French.

Considering an average of 311 litres of water flows out of it every second, though the actual amount varies depending on what time of year it is, you can understand why it's seen as something so valuable and cherished.

The Celts considered it sacred, the Romans used it for drinking water and the French built the 18th century equivalent of a laundrette around it.

The spring has been supplying people with water for centuries, but over time people started to wonder what was down there, with legends suggesting it might be a portal to another world or that a terrible beast lurked beneath the water.

Hundreds of litres of water gush out of the spring every second, but the source has never been found (Henri-Alain SEGALEN/Gamma-Rapho via Getty Images)

There have been a few people who decided to dive into the Fosse Dionne over the years, but it was a long time before they could actually do any exploring since they couldn't get far from the entrance.

Dives into the spring's basin were recorded as early as 1908, but since they didn't have proper equipment they couldn't make it very far, and given the reputation it developed that's probably a good thing.

A dive with tanks was attempted in 1955 but failed to get much further than the entrance to the spring's caves, and another attempt in 1962 likewise met with little success.

The following year another team of divers tried to explore Fosse Dionne, but two of them died and this mysterious complex of waterlogged tunnels which fed the bountiful spring from an unknown source claimed its first recorded kills.

The true size of the tunnels beneath the Fosse Dionne became more apparent, as divers did manage to make it through about 360 metres worth of twisting underwater passageways but were not able to find the source of the spring.

Between 1963 and 1996 there were three attempts at exploring the Fosse Dionne, five of the divers died (Herve CHAMPOLLION/Gamma-Rapho via Getty Images)

The dives continued, as did the deaths when in 1974 two professional divers went into the Fosse Dionne and disappeared completely with their bodies never recovered.

Underwater diving is terribly dangerous and over two decades later in 1996 another diver was hired for an attempt at exploration, only for him to die too.

At this point, three diving expeditions that made it into the depths of the Fosse Dionne had resulted in five deaths, and further attempts were banned for over 20 years.

It wasn't until 2019 that an expedition was finally able to dive into the underwater tunnels and return without any loss of life when Pierre-Éric Deseigne made it 370 metres, though even he was not able to find the source of the spring.

To this day, the source of the spring has never been found, and so much of the twisting labyrinth of tunnels which have claimed the lives of many who tried to explore them remain unmapped.