From American Guide:

THE WORLD’S GREATEST MINERAL SEA

SOAP LAKE, WASHINGTON

“For Stomach Troubles, Constipation, Headache, Rheumatism, or whenever a thorough constitutional remedy is needed, take Soap Lake Capsules. Price 25 cents per box.”

— 1906 advertisement for Soap Lake Remedy Company

At the south end of Washington’s ancient river bed, the Grand Coulee, you’ll find the healing waters of Soap Lake tucked among the columnar basalt cliffs and rim-rock slopes of the central shrub-steppe desert.

Containing 23 different minerals, researchers have determined that the chemistry of the lake has more in common with outer space than it does with Earth’s water. Because the alkalinity of Soap Lake resembles the moons of Jupiter, scientists have studied the lake in an effort to learn about the possibility of life on Mars. 

Our human experience of the lake was nothing short of miraculous, as we polar-bear plunged the coastline on a windy day that topped off at cool 38 degrees. The soap-like waters leave behind an oily film that promises to cure what ails you. The plaque at the beach boldly declares that “…This is indeed a god-given body of water for to cure all the ills of mankind.” 

And if all that isn’t remarkable enough, the city of Soap Lake plans to install a 50-foot Lava Lamp on Main Street. Just because.