The Navy is secretly testing submarines in this glacially deep Idaho lake

Idaho’s biggest lake isn’t on most people’s radar

Lake Pend Oreille sits in Idaho’s northern panhandle, and most Americans have never heard of it. That’s part of what makes it worth the drive.

Ice Age glaciers carved this thing deep into the earth, the mountains close in on all sides, and somewhere at the southern end, the U.S. Navy is quietly testing submarine technology in fresh water.

Say the name “pond-uh-RAY” before you get there, and you’ll sound like you’ve been coming for years.

Ice Age glaciers carved this lake 1,150 feet deep

The numbers on this lake take a second to sink in.

It stretches 43 miles from end to end, covers 148 square miles, and drops more than 1,150 feet at its deepest point, making it the fifth deepest lake in the entire country.

The Selkirk, Cabinet, and Coeur d’Alene mountain ranges press in from every direction. You’re not looking at a flat prairie reservoir.

You’re looking at a glacier-carved trench with peaks rising out of the water on all sides.

A French fur trader named it after the Kalispel people’s jewelry

The Kalispel people lived along these shores long before any European showed up.

When a French fur trader arrived, he noticed the ear-hanging jewelry the Kalispel wore and named the lake “Pend Oreille,” which means “ear pendant” in French. Pull up a map and look at the lake’s shape from above.

It actually looks like a human ear.

Explorer David Thompson built the first trading post here in 1809, but the Kalispel connection runs much deeper than any trading post.

Sandpoint puts you two blocks from the water

About 7,000 people live in Sandpoint, the main town on the lake, and it sits on a peninsula where Lake Pend Oreille meets Sand Creek.

Walk downtown and you’ll pass the historic Panida Theater, local art galleries, and the Cedar Street Bridge Public Market, a marketplace built right on a bridge over Sand Creek where vendors sell food, crafts, and gifts.

Two blocks in any direction and you’re at the water. It’s a small town that doesn’t feel like it’s trying too hard.

City Beach puts a 22-acre park right at your feet

In 1922, the Northern Pacific Railroad donated the land that became Sandpoint City Beach, and the town has been using it ever since.

The park runs 22 acres with sandy swimming areas, volleyball and basketball courts, tennis and pickleball, and a playground. Two marinas sit alongside it for boats and sailboats coming and going.

Stand at the waterline and you’re looking straight down the full length of the lake, 43 miles of water backed by mountains. Downtown is a two-block walk behind you.

Drive 34 miles of shoreline with no subdivisions in sight

Highway 200 traces the lake’s northern and eastern edge for 34 miles, and the state calls it the Pend Oreille Scenic Byway for good reason.

You’ll pass overlooks with pull-offs, interpretive signs, and the small towns of Hope and Clark Fork tucked along the water.

Most of the shoreline on this stretch stays undeveloped, so the wilderness feeling holds the whole way. Come in the fall and the color is dramatic.

Come in winter and the snow-covered peaks above the water are something else entirely.

A 37-pound trout came out of this lake in 1947

Anglers started talking about Lake Pend Oreille in the 1940s when kamloops rainbow trout, a strain from British Columbia’s Kootenay Lake, were transplanted into the water and took off.

The lake’s depth and cold temperatures suited them perfectly. They can grow past 20 pounds, and the Idaho state record sits at 37 pounds, caught here in 1947.

Beyond the Kamloops, the lake holds lake trout, bull trout, kokanee salmon, walleye, northern pike, bass, and perch. Fishing here isn’t one species.

It’s a whole menu.

293,000 sailors trained here during World War II

At the lake’s southern tip, Farragut State Park covers 4,000 acres of land that used to be one of the biggest naval training stations in the world.

During World War II, more than 293,000 sailors came through the Farragut Naval Training Station. At its peak, it was the second-largest naval training center in the country and the largest city in all of Idaho.

The Navy handed the land to the state in 1949, and it became a park in 1965.

The Museum at the Brig, inside the original confinement building, is open Memorial Day through Labor Day.

The Navy still runs submarine tests in this fresh water lake

Not far from the old training station, in the town of Bayview, the U.S. Navy’s Acoustic Research Detachment has been testing submarine technology in Lake Pend Oreille since 1946.

The lake’s extreme depth, calm conditions, and steep forested shoreline replicate open-ocean acoustics closely enough that scale-model submarines go into this water to help engineers develop quieter vessels.

It’s an active military installation, so you won’t be walking up to the fence for a look. But knowing it’s there changes how you see the water.

Schweitzer gets 300 inches of snow and views into three states

Idaho’s largest ski area sits in the Selkirk Mountains about 25 minutes from downtown Sandpoint. Schweitzer Mountain Resort covers 2,900 acres with 92 named runs and averages around 300 inches of snow a year.

On a clear day from the slopes, you can see into three states and across into Canada. When the snow melts, the mountain doesn’t close.

Summer brings hiking, mountain biking, disc golf, a zip line, and scenic chairlift rides with Lake Pend Oreille spread out below you.

Scotchman Peak is 7,009 feet with mountain goats at the top

Scotchman Peak is the highest point in Bonner County, and the trail to the top covers 8.3 miles round-trip with 3,700 feet of elevation gain. It’s a strenuous hike and the summit makes it clear why.

You’ll see Lake Pend Oreille, the Clark Fork River Valley, and the Selkirk Mountains from up there. Mountain goats show up regularly near the top, so give them room.

If that’s more than you’re up for, the Pend d’Oreille Bay Trail near City Beach runs 1.7 miles along the shoreline, nearly flat, and works for any fitness level.

Lake Pend Oreille earns four different trips across four seasons

Summer on the lake means boats, kayaks, paddleboards, and swimmers in the water every day. Fall quiets the crowds and turns the scenic byway into a corridor of color.

Winter shifts everything to Schweitzer, with cross-country skiing and snowshoeing filling the gaps.

Come spring, wildflowers push up through the national forest land and bird migration kicks off at the wildlife refuges to the north.

The national forest surrounding the lake adds hundreds of miles of trails to the options. One season here is never the whole picture.

Visit Kootenai National Wildlife Refuge near Bonners Ferry, Idaho

If you want to round out the trip with a morning of wildlife watching, the Kootenai National Wildlife Refuge sits about 40 miles north of Sandpoint near Bonners Ferry.

The refuge covers 2,774 acres and has logged over 220 bird species and 45 mammal species, including moose, elk, bears, bald eagles, and otters.

A 4.5-mile auto tour route runs through the property, along with hiking trails and a photo blind. Check current access conditions before you go, as ongoing restoration work can affect which routes are open.

Admission is free.

This article was created with AI assistance and human editing.

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