A Skinhole Just Opened Up at Banff's Lake Minnewanka

A ground collapse at Lake Minnewanka has exposed a previously unknown underground structure that may date back to the 1940s, according to Parks Canada.

The feature drew attention after Banff-born local Matt Shakotko posted a video on social media June 6 warning visitors about what he described as a newly opened sinkhole near the popular day-use area. In the video and accompanying caption, Shakotko suggested the hole could be linked to the Bow Valley's mining history.

Parks Canada says staff first identified the feature after responding to a ground collapse on the Lake Minnewanka beach May 9.

"The collapse was caused by the failure of the roof of a previously unknown underground structure located beneath the surface," said Tomi Postma, public relations and communications officer for Banff National Park.

Parks Canada has fenced off the area, warning that the ground around the structure remains unstable. The agency says no risks have been identified beyond the closure.

"For public safety, visitors are asked to stay well clear of the fenced area, as the ground around the structure is unstable and further localized collapse may occur," said Postma.

While social media users speculated the feature may have been linked to historic coal mining activity near Lake Minnewanka that ended in 1922, Parks Canada says initial assessments suggest the buried structure was made of untreated wood and may instead be connected to the area's former campground.

According to Postma, the structure includes log walls and rough-cut planks and is believed to date to before the 1950s or 1960s. Parks Canada has not located any historical plans or photographs identifying the exact purpose or origin of the timber feature.

The agency says the structure may have been associated with the former Lake Minnewanka Campground, which operated in the area until 1952 before being replaced by the newly opened Two Jack Lake Campground and the conversion of the site to day-use facilities.

"It is possible that this feature was related to the Lake Minnewanka Campground and was likely installed in early 1944," said Postma.

The discovery is not the first evidence of historic human activity around Lake Minnewanka. Parks Canada records show the area contains archaeological sites spanning roughly 10,000 years of human occupation, as well as submerged remnants of the former Minnewanka Landing townsite, historic dams, bridges and other structures flooded when the lake was raised following construction of the current dam in 1941.

Parks Canada heritage specialists are now assessing the site to determine the structure's origin and whether it has any archaeological or heritage significance.

"Heritage specialists are assessing the site to better understand the structure's origin and any potential heritage or archaeological significance," Postma said.

The agency says remediation work to stabilize and restore the site will begin once those assessments are complete. In the meantime, Parks Canada is asking visitors to respect fencing and closures around the area.

"We appreciate the public's cooperation in respecting closures and helping to ensure everyone's safety," Postma said.