There's nothing more eerie than being cutoff from the world below the ground, surrounded by darkness with the constant sound of dripping all around you.
Underground spaces, whether manmade or natural, are cold dark and oppressive places. They're often hard to navigate due to their labyrinth-like passageway, making visitors feel lots and disorientated.
Many have a history of witchcraft, murder, death and wartime secrets, so it's no surprise that so many people report strange and paranormal occurrences in these types of locations.
Whether these phenomena are real examples of paranormal, or are just in the mind, there's no denying subterranean places are scary. So with that in mind, let's take a look at the ten most haunted caves, bunkers, tunnel networks and other manmade underground structures hidden beneath the ground all over the UK.
10. Wookey Hole Caves, Wells
The famous show caves are said to be haunted due to their colourful past, most famously its former, a resident witch.
She is said to have cursed a monk from nearby Glastonbury, he came to the caves in search of the witch in an attempt to break the curse. He splashed holy water on the cave walls, which is believed to have turned into the impressive stalagmites visitors can see in the caves today.
9. Covent Garden Underground Station, London
Covent Garden Underground is one of the busiest stations for tourists visiting London, but the station is also said to have been visited by spirits from beyond the grave.
One Christmas Eve a ticket inspector was tormented by a knocking on his office door. When he open the door, he found himself face to face with a tall man wearing a grey suit. The mysterious man said nothing and disappeared into thin air as he walked away.
The same man has been spotted many times since at the underground station, by staff and customers.
8. Greenwich Foot Tunnel, London
Connecting Greenwich and the Isle of Dogs is one of the oldest tunnels under the River Thames, an eerie, 370 metre long pedestrian tunnel. It was opened in 1902 to allow workers from north of the river to easily get to London's docklands without having to catch a ferry.
Many have reported a feeling of unease in the dank subterranean walkway, others say they've felt they've been followed through the tunnel, but a rare few have reported seeing the ghost of a couple walking along the tunnel, the figures promptly vanish into thin air as they are passed by.
7. Elephant & Castle Underground Station, London
South of the river on the Northern and Bakerloo lines is Elephant & Castle station, opened in 1890 and the site of numerous reports of spooky goings on.
Staff and commuters have reported hearing mysterious footsteps running through the station's tunnels and along platforms, as well as doors being slammed and unexplained bangs and tapping sounds. Others claim to have seen the ghostly figure of a woman boarding the trains.
An off duty train driver even reported seeing her on his journey home, he says the woman walked straight through the carriage and he had to move aside as she seemed totally unaware of his existence.
6. Kelvedon Hatch, Brentwood
The 1950s nuclear bunker is spread over three floors and is accessible through a 100 meter long access tunnel from an ordinary looking cottage, on closer inspection it's clear the cottage is far from normal, built with thick concrete walls and windows protected by steel shutters.
Visitors to the bunker, which is now a museum, have reported experiencing poltergeist activity, hearing growls and footsteps coming from empty rooms, and even witnessed full apparitions.
During the bunkers construction under order of the Air Ministry in the 1950s, crews are said to have disturbed an ancient burial ground. A foreman also died during the works. His hard hat was found floating in wet concrete, it's thought he was buried alive in the bunker's three meter thick walls. There's also said to be the ghost of a construction worker who committed suicide in the main stairwell.
5. Edinburgh Vaults, Edinburgh
The Edinburgh Vaults are a network of eerie chambers which are formed in the arches of the South Bridge in Edinburgh. Due to the city's growing population, the 120 rooms or 'vaults' beneath the bridge were put to use to house taverns, workshops for cobblers and other tradesmen in 1788.
The vaults were damp with poor air quality and condition were grim, which resulted in businesses leaving. This meant that the dank caverns were overtaken by Edinburgh's poorest citizens, the homeless and criminals, who carried out activities such as illegal gambling, whisky distillery and even bodysnatching.
Eventually the vaults were filled in and forgotten about, until they were rediscovered in the 1980s and eventually opened as a tourist attraction. Thanks to its depressing past, the vaults are now said to be one of the most haunted places in the UK.
Visitors report hearing disembodied voices, including the sound of children crying. The mysterious sound of feet shuffling can also be heard coming from dark corners of the vaults, and people have reported being touched. During 'Most Haunted's' investigation of the location in 2008, one of their team was scratched by an unseen force, to this day it is still one of the team's most violent investigations.
4. Drakelow Tunnels, Kidderminster
The tunnels were originally excavated to house the Drakelow Underground Dispersal Factory where Rover produced aircraft parts for the Air Ministry, after the Second World War it was refitted and put on standby during the Cold War as a bunker for the local government.
According to newspaper reports at the time, at least three men were killed by a roof fall while digging out the tunnels in the 1940s, there are reports since of factory workers being killed underground after being hit by trucks and while riding conveyor belts.
Modern-day visitors who dare to wander through the darkness have reported hearing strange noises, screaming and cries, and disembodied voices.
The tunnels are believed to have been built under an ancient hill fort which had its own graveyard where hundreds of bodies were buried. During the tunnelling the dead were disturbed and as a result a "demon guardian" of the burial ground is said to take a disliking to anyone who enters the tunnels.
This could account for sightings of a dark shadowy figure which has been seen by visitors. Airsoft participants have pursued fellow players in the darkness, only to turn a corner and find themselves faced with a dead end and no figure anywhere to be seen.
3. Hack Green Nuclear Bunker, Nantwich
Hack Green was first used during the Second World War, its purpose was to confuse German bombers looking for the vital railway junction at Crewe. In the 1950s, the site became part of the ROTOR project and a reinforced concrete bunker was built and became known as RAF Hack Green. After being abandoned for some years, the Home Office took it over and converted the bunker to Regional Government Headquarters which remained in use until 1992.
The bunker is now a museum, and guests and staff have reported paranormal activity, including seeing the apparition of a young woman in the bunker's former telecommunications area. An aggressive male spirit is also said to haunt this area.
In the main corridor witnesses have seen a man dressed in period uniform, or have picked up on a general feeling of unease. Part of the bunker is now a theatre, and here guests have reported being touched and even pushed by an unseen force.
Records show that a settlement has existed on the site of Dover Castle since Saxon times, it has a history of involvement in pirates, Napoleonic battles, and even housed a secret underground command centre in the Second World War.
The battlements are said to be haunted by a the ghost of a headless drummer boy who's believed to have been decapitated when he was attacked for the riches he was carrying while on an errand for his master. The castle is also said to be the home of a woman in red who has been spotted around the castle, as well as a cavalier.
The castle has a haunted underground area too. Below ground in the WWII tunnels, the ghost of many soldiers have been seen and their presence felt. Visitors have reported hearing disembodied voices, loud screams, and doors slamming, as well as experiencing sudden drops in temperature.
1. The Hellfire Caves, West Wycombe
Like Chislehurst Caves, the Hellfire Caves are a manmade network of chalk mines, which extend a quarter of a mile underground near the village of West Wycombe. The caves have a past of satanic rituals, worship and sacrifice, making them a terrifying place to visit today.
The Hellfire Caves are said to have many resident spooks, including the spirit of Benjamin Franklin, who was a regular visitor to the caves in the 18th century. Another apparition regularly spotted is that of Paul Whitehead, a former steward of the notorious Hellfire Club from which the caves take their name.
There's also the spirit of a young girl called Suki, she's said to have been tricked into meeting a man at the caves, the visit resulted in her murder.