Canada’s deepest cave, Bisaro Anima, has become even deeper following a two-week exploration expedition beneath the mountains north of Fernie.

Preliminary results from the late September and early October expedition put the cave at 10.5 kilometres long and 690 metres deep, surpassing the previously reported depth of 682 metres.

Located beneath a mountain plateau approximately 12 kilometres north of Fernie, Bisaro Anima has been the focus of more than a decade of exploration.

Led by Golden resident Katie Graham, the 24-member expedition mapped approximately 1.1 kilometres of additional passages, connected another cave entrance and extended the northern limit of the underground system.

Exploring Canada’s deepest cave

Exploring Bisaro Anima requires months of preparation, transporting equipment through narrow, muddy passages, descending vertical shafts and establishing underground camps in cold, wet conditions.

For Graham and her dive team, this year’s expedition involved hauling twelve bags of specialized equipment through the cave to an underground lake, known to cavers as a sump.

“Most of the crew had never seen the sump before. Their faces lit up with the beauty and intimidation of the teal blue lake,” Graham said.

“The task is daunting but exhilarating. Unraveling the mystery of what is around the corner? Why is the rock like that? It is a combination of time travel, geology field trip, climbing a mountain peak, and camping in the rain – all so we can dive to know the secrets the mountain is hiding.”

The submerged passage continued beyond the divers’ turnaround point, suggesting more discoveries are possible. Further exploration will require a new strategy for transporting sufficient diving equipment through the demanding underground system.

Technology is also helping the team push deeper. For the first time this year, specialized radios enabled communication through solid rock between underground camps, allowing explorers to share progress reports and coordinate logistics.

New discoveries open scientific opportunities

Beyond establishing new exploration records, the discoveries offer opportunities to better understand the geological and biological history of the cave system.

Researchers at the University of Toronto will analyze mineral samples to investigate the age of the deepest passages.

Water samples destined for the University of Montreal will contribute to research into underground microbes and the communities they form in these isolated environments.

The expedition also followed the inaugural UNESCO International Day of Caves and Karst, observed on September 13, 2026.

The international designation recognizes the importance of cave systems and karst landscapes to freshwater supplies, biodiversity and the preservation of geological and human history.

Bisaro Anima named Expedition of the Year

The Royal Canadian Geographical Society (RCGS) selected Bisaro Anima as its 2026 Expedition of the Year, providing financial support for the ambitious exploration project.

The expedition also received funding from the National Speleological Society, helping offset the costs of an otherwise self-funded undertaking by Graham and her teammates.

Bisaro Anima and Graham’s determination to explore its deepest passages were previously featured in the award-winning documentary Subterranean.

Released in 2023, the documentary follows two Canadian cave exploration teams attempting to establish national records. The film received multiple international awards, including Best Adventure Film at the Banff Mountain Film Festival.

More of Bisaro Anima remains unexplored

Despite the latest discoveries, the cave’s full extent remains unknown. Unexplored passages and underwater sections offer opportunities for future expeditions to extend the system farther into the mountains.

The newly mapped passages establish another milestone for the exploration team, but the work is far from complete.

As expedition member Christian Stenner explained:

“The results are a record of what we’ve learned so far, not the limit of what is there. There’s so much more to discover.”