The Blue Lagoon, located in Harpur Hill, Buxton, is a disused quarry that has attracted visitors due to its striking turquoise waters. However, it is now deemed unsafe for swimming due to its highly alkaline water, which poses serious health risks, including contamination from rubbish and dead animals. Amy Cartledge, a risk reduction manager at Derbyshire Fire and Rescue Service, emphasized the dangers of entering the water, as cold water shock can occur quickly. In response to a surge in visitors, especially during warm weather, High Peak Borough Council has reintroduced toxic black dye to the lagoon to deter swimming. This measure was previously implemented from 2017 to 2024 and is now back due to renewed safety concerns. The lagoon is on private property, and police are monitoring the area to enforce swimming prohibitions. The Royal Life Saving Society has reported an increase in accidental drownings during warm weather, highlighting the need for caution in outdoor swimming across the Peak District.