A century or so after the cessation of almost all mining in Cornwall, certain estuaries still have extremely high sediment concentrations of toxic trace metals, particularly copper and arsenic, but also lead and zinc. These high trace metal loadings in the sediments are to a large degree bioavailable to the local infauna, especially sediment-ingesting invertebrates. Some sediment trace metal bioavailabilities are so high as to be of ecotoxicological concern, with deleterious effects on the local biota at levels of biological organization up to and including changed community structure. The estuaries of interest here are those of the Rivers Carnon (Restronguet Creek), Tamar (and Tavy), Gannel, West Looe and Hayle. These estuaries are especially attractive field sites for comparative trace metal ecophysiology and ecotoxicology research for they lack the confounding presence of other anthropogenic contaminants inevitably present in most estuaries in the developed world. The estuaries also offer a range of combinations of different trace metals and a comparative gradient of sediment bioavailabilities of these trace metals.