Diver and nature enthusiast Dawn Watson has been exploring the North Sea off the East coast of England for more than 15 years, but a series of recent events led her to stumble upon something lurking in the waters that she had never seen before: an ancient, prehistoric forest dating back some 10,000 years.

The remains of the forest were discovered around 300 meters off the coast of Norfolk by volunteer Seasearch diver Watson during a trip to study marine life in the area. Shortly into the dive, rough waters near the shore forced Watson slightly off course, which led her to the unexpected site. Watson told the BBC that at first, all she could see was “an enormous wave of black stuff,” but she continued exploring and soon found herself immersed in a huge sprawl of old oak trees, lying flat across the sea floor.

“To start with I thought it was a piece of wreck because it looked like a piece of hull,” Watson explained to the BBC. “It wasn’t until I had a really close look that I realized it was actually solid wood.”

It’s likely that the ancient forest eluded the eyes of explorers for so long because it was buried beneath layers of sediment. But it probably first became exposed when a storm that struck the coast last winter shifted thousands of tons of sand around, revealing the huge collection of tree trunks and branches, some of which are eight meters in length.

According to scientists, the forest is around 10,000 years old and forms part of a prehistoric landmass known as Doggerland, which linked the UK to mainland Europe. Alongside thick forests, Doggerland would have consisted of salt marshes, hills and estuaries. The region was so vast that Mesolithic hunter-gatherers residing in this forgotten country would have once been able to travel on foot to Germany. However, around 20,000 years ago, rising sea levels began to slowly flood the area, transforming it from a wildlife-rich paradise to a low-lying, marshy island. Tribes were eventually forced out of the area over time, but stragglers were probably wiped out by a tsunami that triggered a catastrophic sub-sea landslide some 8,000 years ago.

Fishing boats trawling the North Sea have dragged up a plethora of relics from the inhabitants of this prehistoric world, including animal bones, human remains and artifacts such as axes and bone points. However, scientists had no idea that remnants of the forest still existed so close to the UK’s East coast. Now that the veil has been lifted, Watson and her partner Rob Spray will continue to survey the marine life that inhabits the ancient forest, which has been transformed into a natural reef housing an abundance of diverse organisms.

[Via BBC News, Reuters, The Independent, Washington Post and Science Alert]