Upper Valley Bulletin Board
Serving the Communities of Naches, Gleed, Cowiche, Tieton and Nile Valley

Gateway to the Cascade Mountains
and Yakima Wine Country


Welcome to the Upper Valley Bulletin Board
If you'd like to support this community information effort, please complete the "Support the UVBB" form and mail it in with your check!
Naches Visitors Center


Home > Visitor Information

Boulder Cave: An Adventure in Nature

Boulder Cave Closed
Access to Boulder Cave closed until Memorial Day weekend - 2017.


Protect the Bats: Please follow ranger's instructions to brush your shoes and scrape them on the astroturf before entering the cave to protect the bats from the unwanted spread of White-Nose Syndrome. learn more

Boulder Cave

Boulder Cave Day Use is normally open by Memorial Day weekend and stays open through the end of September. Check with the Naches Ranger Station in early spring and late fall for confirmation that it's open.

This area is managed by the Forest Service. There is a charge of $5.00 per vehicle per day for parking, which includes buses. Northwest Forest Pass, America the Beautiful - National Parks and Federal Recreational Lands Pass and Interagency Senior/Access passes can be used in lieu of the payment of the $5, if they are displayed properly and the card holder has identification.

The cave attracts in excess of 35 thousand visitors a year!

This day use site is open 8 a.m. to dusk; the main access gate is closed at dusk each night. There is a two hour limited parking for those parking in the trailhead parking area.

An interpreter is on site throughout the week at Boulder Cave to provide programs associated with the geology and history of the area as well as provide a background on the need to protect the declining bat population.  Interpreters also monitor the use of Boulder Cave, Boulder Cave Trail, and the River Walk Trail.

School tours and individual group tours may be arranged by calling Doug Jenkins or Shirley Whitney at (509) 653-1401.

Those using Boulder Cave Trail and visiting the cave will find updated signs and trash containers along the trail and at the cave.  Please follow posted signs which emphasize staying on the trail and observing all the rules.

Location / Directions

Boulder Cave is located near Milepost Marker 95.43 on SR410, approx. 32 miles west of Naches. There is a sign on the road pointing towards Boulder Cave.

Coming from the east (Yakima/Naches towards Chinook Pass), just past Cliffdell turn left at the first road past Whistlin' Jack Lodge - Forest Service Road #1706.

Coming from the west (Enumclaw) the turn is just before Whistlin' Jack Lodge. Turn to the right on Forest Service road #1706.

After you turn onto FS Road #1706 you will cross a bridge. Follow the signs to Boulder Cave, approximately 1.4 miles to the right after you cross the bridge.

Pets are allowed along the trail as long as they are kept on a leash and owners clean up after them.

Boulder Cave Trail

BatsThe Boulder Cave Trail is less than 2 miles long round trip and normally takes about an hour for the round trip. The trail gains about 200 feet in elevation and can be slippery in places. The gravel trail runs along the edge of a deep ravine, climbing gradually through a forest of Douglas-fir and Ponderosa pine. Devil's Creek flows through the bottom of the ravine, framed by trees and several species of broad leafed shrubs. In autumn, the golden tones of the leaves splash new color across the landscape, contrasting sharply with the evergreen forest.

Approximately 400 feet from the cave, the trail narrows and descends to bring the visitor to the entrance. A strong flashlight is useful in the center portion of the cave. A good pair of walking shoes, layered clothing, and some water is also needed. A visit to the cave is a cool treat on a warm summer day.

In the canyon’s cool shadow, notice how the plants differ from those growing on the sunny ridge. As the cave engulfs you, let some of the other senses explore the darkness. Feel the moisture in the air. Listen to the creek. Lava that once flowed hot is now cold and hard to the touch. This is a unique cave. The Boulder Cave trail was built by the Civilian Conservation Corps (CCC) in 1935. With the voluntary help of a local stone mason, the trail was improved by the Youth Conservation Corps (YCC) in 1987.

The Formation of Boulder Cave

Boulder Cave - Chinook PassHow was Boulder Cave created?

Caves are unusual in the northwest, and Boulder Cave is the largest, most extensive cave of its kind. When most people think of caves, a limestone caverns or lava tubes come to mind. Boulder Cave is unlike any cave you have ever been in before. It took millions of years of volcanic action to create this landscape, and thousands of years for erosion and weathering to shape the features you’ll see on your visit.

Over thousands of years, lava flows occurred periodically in the Yakima basin and covered deposits of soft, loose rock and soil. The lava cooled, forming hard layers of basalt, and trapping the softer layers of loose sediment between.

Next, water went to work. Water is a patient sculptor, etching it’s signature into the basalt for thousands of years. The water is now carving though soft sedimentary layers of loose rock, soil, and ash deposited between lava flows. The stream is busy cutting out a new cave. This is how Boulder Cave may have looked if you visited Devil’s Creek thousands of years ago.

At Boulder Cave, the water flowing in Devil's Creek eroded a deep channel through the top layer of hard basalt and the softer layer of deposits beneath. When Devil’s Creek met the next layer of hard basalt, the creek stopped its downward action and instead continued to erode the softer deposits horizontally. In time, the horizontal erosion carved a hollow pocket underneath the top layer of basalt.

Approximately 25,000 years ago, the outer edge of this pocket weakened and collapsed into the hollow below, leaving an archway 350 feet long and 30 feet wide - Boulder Cave!! Today, Devil's Creek still flows through the cave that it created. The formation of Boulder Cave is unusual - most caves are old lava tubes or are formed from groundwater dissolving layers of limestone.

Chinook Scenic BywayRiver Trail

The River trail runs north of the trailhead. It is a 3/4 mile barrier free paved loop designed to provide easy access to the Naches River for everyone. Users can leisurely admire nature's beauty or fish along the Naches River (see State Fishing Regulations for more specific information). Resting benches and quaint wooden bridges encourage visitors to linger and enjoy the sights and sounds of the out-of-doors.

Along the River Trail

Green ribbons of life: Riparian areas are the vibrant green realms lining a waterway or lake. Logs, rocks, and gravel move in and out, creating a constantly changing landscape. You will find this place always in a flex, one plant battling another for dominance. A healthy riparian area will have plants that provide food, shade, and shelter. For the same reasons we seek these quiet places, so do the animals, birds, and fish.

Bountiful haven: This tranquil creek is unique in several ways. It was man-made rearing ground for juvenile salmon. Fingerlings spend their first year here. Stream-side plants offer shade to cool the water from the sun and food to nurture young fish. Logs in the water provide refuge from predators. The side channel, completed in 1990 was done by the U.S. Forest Service and Trout Unlimited. If you would like to help with such a project, contact a chapter of Trout Unlimited near you to volunteer.

Boulder Cave near NachesBeyond the river’s flow: The plants here have transformed from lush riparian vegetation near the river to drier upland grass and flower meadows. Grassland is an area where water is collected, absorbed, and percolated through the soil and into the watershed below. Abundant grasses hold a watershed together. This will happen in downstream waters also.

River ghost – paths of the past: This was once the bed of the Naches River. You can see dry wash areas and small knolls created by the water’s current. Imagine how the old river threaded its way into pools on this flood plain. A river is alive and ever changing. It’s a restless soul and always searching for a new course to travel.

Boulder Cave Picnic Area

In the 1920s, the Forest Service created Boulder Cave Recreation Area for visitors to discover the natural wonders of the cave for themselves. A picnic area, located near Boulder Cave Trailhead, is enhanced by a group shelter with a large stone fireplace that was built by the CCC in 1935. The shelter can not be reserved, but is available on a first-come, first-served basis. Drinking water is supplied by a few healthy tugs on an old fashioned hand pump at the picnic area, but not along the Boulder Cave or River Trail. Picnic tables, fire rings, and a barrier free composting toilet are also on site.

Other Area Opportunities

Opportunities for overnight camping along the Naches River are nearby. Sawmill Flat Campground, Halfway Flat Campground and Little Naches Campground are developed sites that are located within five miles of the Boulder Cave Trailhead. Sawmill Flat offers barrier free restrooms and sites suitable for larger recreational vehicles. Food, gas, and lodging are located as close as Cliffdell, two miles from the Boulder Cave Trailhead.

Big-Eared Bat Hibernaculum

BOULDER CAVE CLOSED October 1st TO May 1st for protection of the Townsends Big Eared bats.

BATS: Boulder Cave is home to the only known population of Pacific Western Big-Eared Bats in this part of Washington State. The Pacific Western Big-Eared Bat is listed as a sensitive species in Washington and Oregon. A small population of 50 bats use Boulder Cave as a hibernaculum’s during the winter. In the 1920s and 1930s, the Boulder Cave bat population numbered in the thousands. These bats have historically used Boulder Cave during the summer, but presently do not. The big-eared bat is extremely intolerable to human disturbance. It appears the heavy human use during the summer has discouraged the big-eared bat's use.

By implementing the following guidelines, you could help encourage the bat to use Boulder Cave again.

  • Please observe the following in the cave:
  • Limit conversation and all noise. Whisper if you must talk.
  • Stay on the trail and don't double back.
  • Use dim flash lights. Keep the beam directed at the trail.
  • Don't build campfires in the cave.

If you see any sick, oddly behaving or dead bats, please report them to the Department of Fish and Wildlife.

Thank you for your help!

Boulder Cave and Trail #962 leading to Boulder Cave are closed from October 1 to May 1 to all visitor use. Forest Service Road #1704 is closed to four-wheeled vehicles from Camp Roganunda to the washout (approx. 1 mile NW) during the same time period. The reason for these closures is to discourage vandalism, public safety (trail and cave have hazardous ice conditions during the winter), and to protect a sensitive species of bat (Pacific Western big-eared bat).

This highly beneficial species is in rapid decline due to disturbance during hibernation. Bats must survive the winter months on a limited supply of stored fat; any disturbance that may awaken bats will deplete this food supply resulting in their death. Humans within sight or sound of the bats create sufficient disturbance to awaken them.

Our thanks to the Naches Ranger District of the Okanogan and Wenatchee National Forests for providing this information on Boulder Cave.


Updated July 2, 2016


Upper Valley Bulletin Board
P.O. Box 881 | Naches, Washington 98937
Tel. (509) 966-1529