The gates to hell might be down here on Earth

But whether you believe in heaven and hell or not, most people probably don't think you can access either from Earth.

However, there are some who have put a lot of time and effort into trying to establish if there are 'entrances to the underworld' on planet Earth.

These are the five locations that have strong claims to being real-world 'gates to hell.'

Gehenna, Israel

In his 'Sermon on the Mount' Jesus famously warned that anyone who allows their hand or eye to sin will be cast into 'hell'.

However, some biblical experts believe he actually said 'Gehenna' instead of 'hell,' the Daily Mail reports.

This is a real location just outside the walls of old Jerusalem, and is one of the deep gorges which can be found to the southwest of the old city.

It was believed Gehenna was a particularly evil place, having been the location where ancient Israelites practiced child sacrifice, according to the Bible.

When the Bible was translated, the word Gehenna was gradually swapped for the English word Hell. So, Gehenna has a claim for literally being hell on Earth.

St Patrick's Purgatory, Ireland

This Irish island was considered by early medieval people to be the edge of the known world. St Patrick prayed to God for a way to convert the Irish pagans, and his efforts were rewarded by a vision of a 'pit of purgatory'.

According to medieval texts, this pit is located on Station Island where a monastery founded by one of St Patrick's disciples still stands today.

The cave was filled in in the year 1790, and a large chapel now sits on the site, which is a popular pilgrimage site in Europe.

Hierapolis, Turkey

This ancient Roman city had an entrance to a small door leading into a cave-like grotto built into one wall of an open arena.

This door was known as Plutonium. According to ancient philosopher Strabo, sacrificial animals would be lead down here before dying the moment they reached the door.

Scientists later found out that the door sits on an active volcanic fault line, producing thick clouds of CO2 which would rise up out of the cave.

These gases were so strong, they could kill insects, birds, and mammals, a 2018 study found.

Actun Tunichil Muknal, Belize

Meaning the Cave of the Stone Sepulcher, the Actun Tunichil Muknal lay undiscovered and undisturbed for more than 1,000 years after the collapse of the Mayan Empire.

The cave is more than three miles deep in the Earth and archaeologists have found artefacts dating back to around 800 AD.

Just to round off its 'gate to hell' credentials, is filled with the remains of the victims of human sacrifice.

When archaeologists discovered the cave in 1989, they found the remains of some as young as four-year-old, who had been bludgeoned to death.

Experts think the cave was believed to be the entrance to Xibalba, the Mayan underworld and the domain of the death gods.

Hekla Fell, Iceland

Just by looking at this place, you can understand why it was believed to be an entrance to hell.

Hekla is a 1,491-metre volcano in Southern Iceland, which had a massive eruption in 1104 after being dormant.

The eruption covered 21,000 square miles in rock and ash, with news of the apocalyptic event managing to make it around the globe.

Medievel authors wrote hellish accounts of the eruption, including 16th-century German scholar Caspar Peucer who famously said the gates to hell could be found in "the bottomless abyss of Hekla Fell."