Cornwall’s history as a mining region has left a lasting mark on its landscape. Beneath the surface lie more than 20,000 abandoned mine shafts, some of which are now unstable. In recent years, a number of collapses have occurred, drawing attention to the hidden risks below homes, roads, and public spaces.

In February 2020, a tree fell in a garden in Camborne during a storm. Soon after, the ground opened up, revealing a forgotten mine that had been buried beneath the property for roughly 200 years. The hole initially measured about three feet wide, but it grew quickly. Within a day, it had expanded to the size of a small house, damaging part of a nearby road and disrupting electricity and water lines. Engineers later determined that heavy rain and the weight of the fallen tree had weakened the soil above the old shaft, triggering the collapse.

Similar incidents have occurred elsewhere in Cornwall. In St Austell, a hole appeared in the middle of Bucklers Lane, prompting residents and local authorities to warn drivers and pedestrians to avoid the damaged section of the road. In the nearby Biscovey area, a resident is reported to have died in the 1990s after an old mineshaft opened up on their property. At Par Golf Club, a 30-foot-deep mining shaft appeared near the second fairway after extreme rainfall. No one was injured, but engineers were called in to assess whether other parts of the course were at risk.

In November 2025, a parked car sank into a hole about six and a half feet deep behind Barryman’s Bakery in Redruth. No one was inside the vehicle, and there were no injuries. Witnesses reported that rubble continued to fall into the opening after the initial collapse, indicating that the surrounding ground remained unstable. The incident was likely linked to an old mining feature rather than a typical sinkhole, which forms when water dissolves rock underground. In this case, an underground tunnel or shaft lost support and caved in.

Repairing such collapses is not straightforward. Engineers must first map the underground space using test holes, cameras, and scanning equipment. Heavy machinery must be used with care, as large vehicles can place additional pressure on weak ground and lead to further collapse. Once the problem is understood, the usual approach involves digging down to the shaft, adding a strong concrete cover, and filling the space with specially designed material. The surface is then rebuilt.

The cost of these repairs varies widely, ranging from about $6,000 to more than $300,000, depending on the size and complexity of the issue. Some collapses can also trigger others, as nearby unstable shafts may be waiting for the right conditions to give way. Near Perranporth Beach, three additional holes appeared in sand dunes above the old Wheal Remfry mine, which once reached about 300 feet underground. The area was fenced off to prevent access.

Cornwall’s mining industry reached its peak in the 18th and 19th centuries, and many abandoned mines were never properly mapped. As a result, some shafts remain unknown today. Mining activity is now returning to the region, with plans to reopen South Crofty, the last large tin mine, which closed in 1998. Cornwall is also becoming a source of lithium, a key material for rechargeable batteries. For those buying property in the area, checking for old mine workings is a standard part of the process.