The largest UNESCO World Heritage Site in the UK is found in Cornwall and west Devon, and its designation is based specifically on its heritage for metalliferous mining, especially tin, copper and arsenic. With a history of over 2000 years of mining, SW England is exceptional in the nature and extent of its mining landscape. The mining for metallic ores, and more recently for kaolin, is a function of the distinctive geology of the region. The mining hazards that are encountered in areas of metallic mines are a function of: the Paleozoic rocks; the predominant steeply dipping nature of mineral veins and consequent shaft mining; the great depth and complexity of some of the mines; the waste derived from processing metallic ores; the long history of exploitation; and the contamination associated with various by-products of primary ore-processing, refining and smelting, notably arsenic. The hazards associated with kaolin mining are mainly related to the volume of the inert waste products and the need to maintain stable spoil tips, and the depth of the various tailings’ ponds and pits. The extent of mining in Cornwall and Devon has resulted in the counties being leaders in mining heritage preservation and the treatment and remediation of mining-related hazards.