A 10,000 year-old prehistoric forest off the coast of Norfolk, U.K. Dawn Watson was diving in the North Sea off the coast of Cley next to the Sea, which experts believe is near the site of a prehistoric forest. (Rob Spray/Rex/REX USA)

Dawn Watson has been diving in the North Sea off the coast of England for 16 years, according to the Daily Mail. But it wasn't until rough waters forced the 45-year-old further off shore that she discovered a "long blackened ridge" hidden beneath the waves.

Watson kept swimming until she found herself surrounded by entire tree trunks and branches shrouded in sea animals and plant life, the beginnings of an underwater forest that looked like it had been felled in this lifetime, the paper reported.

"To start with I actually thought it was a piece of wreck," Watson, who heads a U.K. charity dedicated to marine conservation, told the BBC. "It just looked like a piece of hull. It wasn't until I had a really close look that I realized it was actually solid wood."

Scientists now believe Watson actually wandered into the remnants of a vast, ancient forest that stretched from the Great Britain to Continental Europe at one time, according to the BBC. Experts think the forest disappeared when ice caps melted and sea levels rose nearly 400 feet, according to the Daily mail.

Watson told the BBC she thinks she may have found oak trees that were knocked over by outwash from a glacier. Today, they form a natural reef that is teeming with animal and plant life.

"You certainly don't expect to go out for a quick dive and find a forest," she told the Daily Mail. 

The prehistoric forest carpeted parts of a landmass known as "Doggerland," which disappeared under rising sea levels more than 6,000 years ago, according to the BBC. Experts believe the forest could be as old as 10,000 years, the BBC reported.

Some researchers think Doggerland was even the site of a "prehistoric Atlantis" before it was wiped out by an epic tsunami, according to the BBC. Archeologists continue to find evidence under the North Sea that the area was inhabited by Mesolithic tribes and a flourishing culture, according to the BBC, which described the area this way:

By around 10,000 years ago, the area would still have been one of the richest areas for hunting, fishing and fowling (bird catching) in Europe.

A large freshwater basin occupied the centre of Doggerland, fed by the River Thames from the west and by the Rhine in the east. Its lagoons, marshes and mudflats would have been a haven for wildlife.

"In Mesolithic times, this was paradise," explained Bernhard Weninger, from the University of Cologne in Germany, who was not involved with the present study.

Rob Spray, who is working with Watson to survey the forest, called the find "miraculous" and told the Daily Mail that geologists are very excited about it. To get a better understanding of what it looked like, picture a scene from Lord of the Rings, he said.

"At one time it would have been a full-blown Tolkein-style forest, stretching for hundreds of miles," Rob Spray, who is working with Watson to survey the forest, told the Daily Mail. "It would have grown and grown and in those days there would have been no one to fell it so the forest would have been massive."

Watson and Spray plan to continue exploring the forest and hope radio carbon dating can be used to give them a clearer picture of its age, according to the Daily Mail.

"It is extremely exciting as it may be hiding lots of undiscovered fossils of mammoths and sea creatures," Spray told the Daily Mail.