Blue Lake, at St Bathans, was formed by extensive mining activity with a rush starting in 1864, as gold-seeking miners chipped and sluiced their way through the quartz rock of the 120 metre high Kildare Hill. By 1933 the hill had become a 168 metre deep pit. From the 1880s, up to 2000 miners used hydraulic lift technology, like a giant vacuum cleaner, to suck water and gravel out of the pit to where it could be worked for gold. Mining was halted in 1934 because the sides of the pit were getting too close to the town and the huge hole was allowed to fill with water to create today's beautiful lake. The minerals in the surrounding rocks give the water an astonishing blue colour which is offset by surrounding columns of white quartz tailings.br/br/The former gold and coal mining town of St Bathans is found in the Maniototo in New Zealand's Otago region.