The tunnel in Guizhou Province, China, became the focus of investigation after hundreds of people reported going back in time once they exited the 400-metre structure.
Most people reported gaining an hour in time after continuing their drive outside the tunnel, as their mobile phones had gone back exactly 60 minutes.
The phenomena became so well known that one journalist working for the Gui Yang Evening News decided to carry out an experiment.
He drove through the tunnel – an about five minute journey – ten times, and reported gaining an hour on eight of the trips.
With no apparent explanation, and the time gain baffling so many people, conspiracies and theories have abounded online, including everything from real time travel to alien abductions.
One person posted on neowin.net: “Clearly the drivers have missing time, and were probed by aliens.”
Another said: “Maybe the reason why China has so many of the worlds longest living people is not so much because they’re old, but because they spend so long stuck in traffic driving through magic time travel space tunnels.”
Another said: “This sounds wacky, must be a time tunnel, for sure.”
But those who experienced gaining the hour, said they soon lost it again after driving further away from the tunnel.
Local TV media said science had come up with a mundane explanation.
It was said to be later found that a phone transmitter on one side of the tunnel was sending out an incorrect signal, which put phone clock’s times back by an hour, and it was put right after they zapped a correct one further up the road.
Others have suggested it is a magnetic anomaly.