In Buxton, England, there is a pool of water known as the Blue Lagoon, and it is disgusting. Its pH approaches that of ammonia. Local officials have said that it’s so toxic, it’s too dangerous to drain. You would think people would stay away, especially with signs like these, which, Atlas Obscura says, warn would-be swimmers away:

“Warning! Polluted water Lagoon known to contain: Car Wrecks, Dead Animals, Excrement, Rubbish” and “Warning! Do not enter water, due to high pH levels. This can cause: Skin and eye irritations, Stomach Problems, Fungal infections such as thrush” and “Think! would you swim in ammonia or bleach?”

But. But. It looks so inviting:

pool1
alixwilliams
pool2
Simon Harrod

So, in June, the local town council came up with a new solution to keep people out. They dyed the lagoon black:

So far, they say, it’s working. As long as you don’t consider “working” to mean “cleaning up the lake at all.”