(CNN) — Not even a nationwide lockdown could stop England's Instagrammers from flocking to a former limestone quarry in Harpur Hill, whose bright blue waters have earned it the nickname, "Blue Lagoon."

So police did what they had to do to stop visitors from coming. They dyed it black.

"If you don't follow the rules, the police will have the power to enforce them," said Johnson, who himself has tested positive for coronavirus.

Despite this order, police said people were still visiting the disused quarry, which has become a popular tourist attraction.

What the "Blue Lagoon" looked like before it was dyed black. Buxton Police SNT

"With this in mind, we have attended the location this morning and used water dye to make the water look less appealing," the Buxton police department said in a Facebook post Wednesday. "Please stay at home."

This isn't the first time the picturesque body of water, near Buxton and about three hours northwest of London, has been dyed black, according to police. While the lagoon may look like a tropical getaway, officials say the water contans toxic chemicals and has a pH level of 11.3, according to the BBC. For reference, laundry bleach has a pH level of about 12.

Signs around the lagoon even warn tourists that the water contains cars, dead animals and trash. So police regularly dye the water to prevent people from swimming in it.

The move by Buxton police comes as the number of coronavirus cases in the UK continue to rise. As of Sunday there were at least 19,772 confirmed cases and 1,228 deaths, according to Johns Hopkins University.

Johnson says he is sending a letter to 30 million households across the UK to urge people to stay home.