This image shows contours of bathymetry data that was obtained from an echo sounder/GPS survey of the flooded Mount Morgan Mine pit in Queensland Australia. The mine started in the 1880s and finished in 1987. There used to be a mountain where the pit now is.

The bathymetry contours are overlaid on an air photo of the old mine workings. The flooded mine pit is 2.4km long and 43m deep with highly acidic water (pH 3-4).

This map was created with Surfer 7 from about 5000 data points collected (carefully!) in a small dinghy with an outboard. The mine pit may overflow into an adjacent river in the next year or two so volumes were needed to be estimated.