Soap Lake is a unique mineral lake in Washington state, situated in the Grand Coulee Valley, approximately six miles from the town of Ephrata. The lake is famous for its foam and slippery feel, which gives it the name “Soap.”

It has long been thought to offer healing and relaxing benefits.

Before settlers arrived, Native American tribes called the lake “Smokiam,” meaning “healing waters,” and “Let-to-to-weints,” meaning “healing water springs.” Later, European settlers dubbed it “Sanitarium Lake” because people believed the lake could treat health problems.

The lake isn’t as hot as typical hot springs; people visit to enjoy the mineral water and mud treatments. The mud (especially the “blue mud,” found deeper in the lake) is rich in minerals. Visitors will spread it on their bodies, let it dry, then wash it off. It’s claimed to help with skin conditions (like eczema or psoriasis), joint pain, arthritis, and stress.

Because the water is dense, swimmers can float easily, similar to the Dead Sea.

You can visit Soap Lake via public beaches (east or west) or stay at one of several nearby lakeside resorts.

Some facts to remember: the lake’s elevation is about 1,106 ft, you don’t have to pay a day-use fee, and it’s open seasonally.

Geological Formation and Unique Chemistry of Soap Lake

The lake formed during the Ice Age. Groundwater filtered through layers of basalt rock and picked up minerals along the way, creating a solution rich in many elements. Soap Lake contains 23 different minerals, including sodium, calcium, magnesium, sulfate, and carbonate.

The lake also holds ichthyol, a rare organic substance with anti-inflammatory qualities. The water is very alkaline (with a pH of about 9.8), giving it a slippery feel. This alkalinity also helps stop bacteria from growing.

One of its most interesting scientific traits is that the water divides into two layers that don’t mix. The bottom is colder, full of sulfides, and low in oxygen. The top layer is warmer and contains fewer of those chemicals. The boundary between these two layers is called a “chemocline.”

Rockhounding near Soap Lake

Staying near Soap Lake when you visit the area for rockhounding purposes is a great idea. The area is famous for its mineral-rich waters, but the surrounding region is also an excellent destination for rockhounding.

The Grand Coulee and Columbia River Basin are rich in Ice Age flood deposits, basalt cliffs, and gravel bars that conceal agates, jasper, chalcedony, and petrified wood.

One of the best nearby destinations is Saddle Mountain, just east of Soap Lake. This area is known for thundereggs, petrified wood, and opalized wood. A little farther south, the Ginkgo Petrified Forest State Park at Vantage showcases some of the finest examples of petrified wood in Washington.

The Columbia River and its tributaries provide additional opportunities. Gravel bars along the river can yield agates, jasper, and quartz. The Umtanum River area, south of Ellensburg, is another productive site where collectors often find agates and petrified wood.

If you’re willing to travel west into the Cascade foothills, the Little Naches River and its area is a well-known rockhounding area where thundereggs, blue-gray chalcedony, agates, and jasper can be collected in the gravels and along the riverbanks.

Together, these sites make Soap Lake not only a geological wonder for its mineral waters but also a convenient base for exploring some of central Washington’s most rewarding rockhounding areas.

Visitors to Soap Lake have several options for staying close to the water. Lakeside resorts like Soap Lake Natural Spa & Resort and Masters Inn are popular choices, offering easy access to the lake throughout your stay.

Soap Lake Natural Spa & Resort is a favorite for its combination of comfort and wellness. Guests can enjoy spa treatments, mud therapies, and the mineral-rich lake, all while staying in rooms with views of the water.

Reserve Your Stay near Soap Lake Shoreline at Soap Lake Natural Spa & Resort

Masters Inn is a budget-friendly option that provides basic comforts, including Wi-Fi, TV, and mini-fridges. Some rooms also feature kitchenettes, making it convenient for more extended stays.

Reserve Your Stay near Soap Lake at Masters Inn

For travelers seeking more options, the town of Ephrata, just 6 miles away, has additional hotels and motels.

Lodging at Soap Lake

Those seeking a more private or flexible stay can find vacation rentals along the lakeshore, offering self-contained accommodations with easy access to the lake and its mineral-rich waters.

Affordable vacation rentals for short and long term stay at Soap Lake