Huge 1,000-Year-Old Stone Structure Found Underwater in Norway May Be an Ancient Whale Trap

A remarkable underwater discovery off the coast of western Norway is shedding new light on medieval hunting traditions. Archaeologists have identified a large, man-made belt of stones lying across a narrow strait near Øygarden, close to the city of Bergen. The structure, stretching more than 25 meters across the seabed, may be the remains of a thousand-year-old system used to trap whales in coastal waters.

The find offers rare physical evidence of a hunting practice previously known mostly from historical texts. According to marine archaeologist Elling Utvik Wammer of the Norwegian Maritime Museum, the site could be the first confirmed underwater archaeological proof connected to descriptions in the ancient Gulating Law, the oldest surviving record of Norwegian legal traditions.

A Rare Archaeological Discovery Beneath the Sea

The discovery was made during a series of winter dives conducted in January in Grindasundet, a narrow channel near the village of Telavåg. Researchers were investigating potential remains of historic coastal hunting installations—sites where communities once captured both whales and large schools of fish.

During sonar mapping of the seabed, the research team noticed an unusual feature. Instead of the smooth sandy bottom typical for the area, they detected a long concentration of stones forming a continuous band across the strait.

“We saw a distinct belt of stones that ran across the strait. It was exactly what we had hoped for,” Wammer explained.

The structure measures more than 25 meters in length and up to nine meters in width. The stones appear deliberately arranged and partially stacked on one another, suggesting that they were placed there intentionally by humans rather than deposited naturally by currents.

Nearby, the team also detected a second structure: a large circular mound of rocks roughly 15 meters across and rising about four meters high.

As reported by Science Norway, both formations strongly indicate large-scale human construction efforts in the area.

Evidence of Medieval Whaling Practices

Researchers believe the stone belt may have served as part of a barrier system used to trap whales inside a bay. Historical accounts from the 1500s describe a gate or barrier positioned at the same location in Telavåg.

The barrier likely consisted of timber and ropes weighted down with stones, forming a structure that could block the narrow channel leading out of the bay. A net would close the other entrance, effectively trapping whales inside once they had been driven into the area.

Driving whales into enclosed bays was a known hunting strategy in western Norway and is specifically mentioned in the Gulating Law, which dates back to around the 900s.

Wammer notes that the newly discovered stone belt may represent the foundation of this barrier system.

“The newly discovered underwater archaeological site is very unusual,” he said, emphasizing that such structures have rarely been preserved or documented beneath the sea.

A Community-Wide Hunting Tradition

Historical records describe whaling in these coastal communities as a large collective effort involving entire villages.

When whales were spotted entering a bay, someone would alert the settlement. The first step was to quickly block the strait to prevent the animals from escaping.

Hunters would then attack the whales using crossbows and arrows. Some arrows were reportedly treated with bacteria from spoiled meat to weaken the animals.

Once exhausted, the whales were harpooned and gradually pulled toward the shore using multiple rowing boats.

The process could take days. Historical eyewitness accounts from the 19th century describe injured whales swimming around the bay for extended periods before finally being killed.

While brutal by modern standards, such hunting methods were once essential for survival in coastal communities. Whale meat and bones provided valuable food and materials that were shared among villagers according to established rules.

Mystery of the Massive Stone Mound

The large circular mound discovered near the stone belt may be connected to later attempts to alter the strait.

According to records from the 1700s, a local priest named Andreas Christie wrote that villagers tried to replace the original wooden barrier with a permanent stone wall. However, the effort was eventually abandoned because the project required enormous amounts of rock.

The newly discovered mound could be evidence of that failed construction attempt.

“The amount of rock is surprising,” Wammer noted. “They must have transported stones by boat and dumped them into the water.”

This suggests that local communities invested significant labor and resources into maintaining or replacing the barrier system.

Modern Technology Reveals the Past

To document the underwater structures, divers used a photogrammetry technique involving GoPro cameras mounted on a pole. The system captured photographs every second as divers swam slowly across the formations.

Thousands of overlapping images were then processed to create detailed three-dimensional models of the site.

This technology has become increasingly important in underwater archaeology, where dive times are limited and conditions can change rapidly.

Winter conditions actually helped the research team. Cold water contains very little algae, making the sea unusually clear and improving visibility for divers.

A Window Into Norway’s Coastal History

The Telavåg discovery provides valuable insight into how medieval communities engineered their landscapes to support hunting and fishing.

Researchers now believe they may have identified both the exact location of the historic barrier and the remains of later attempts to modify it.

Further fieldwork is planned for June, when archaeologists will return to Øygarden to study nearby fishing sites where stone walls and nets were used to trap large numbers of fish.

A full scientific study of the findings is expected to be published later this year.

For historians and archaeologists, the underwater stone belt represents more than just an unusual structure—it offers a rare glimpse into the ingenuity and resourcefulness of Norway’s coastal societies nearly a millennium ago.

Cover Image Credit: Photogrammetry/oblique photo of the rock structures that were discovered. The mound is on the left, and the stone belt is on the right. Credit: Christopher F. Kvæstad, 3D model: Beatrice Frabetti / IRMAS