A lake in the Bavarian Alps has turned a deep purple color. Reports say it comes from sulfur bacteria that made its way to the water’s surface. Visitors don’t have to worry about toxicity because the bacteria is reportedly only dangerous in enclosed spaces. While the science behind it is interesting, the people flocking to the lake are really more interested in its aesthetic.  Explaining the reason why the lake's water color turned purple, the authorities determined that it was due to purple sulfur bacteria (PSB) entering the lake water. This type of bacteria thrives in anoxic, anaerobic areas such as ponds and lakes, especially in the summer months.  Currently, visitors can still come close to admire the lake because this type of bacteria is only dangerous in closed spaces. These purple sulfur bacteria will eventually sink to the bottom of the lake. In 2020 and 2021, a similar phenomenon occurred at this quarry lake, causing the lake water to turn purple.  The quarry lake is an artificial lake dug during the mining process. During mining, the lake will have no water. When the mine stops exploiting, groundwater and rainwater accumulate to form a lake. The depth of the lake will depend on the rainfall of each region. Quarry lake is also known by another name as pit lake. Although the water in the quarry lake is very clear, it is still very harmful to humans because the mining process has left a large amount of dissolved minerals in the water such as lime, asbestos, granite powder and heavy metals.