Idaho’s deepest lake is hiding America’s submarine secrets

The Navy’s Secret Submarine Laboratory at Lake Pend Oreille

Idaho’s Lake Pend Oreille hides a secret naval lab that’s shaped history since the 1960s.

When the Navy kept 30 acres after closing Farragut Naval Training Station in 1946, they found a perfect testing ground – 1,150 feet deep with a flat muddy bottom and constant 39-degree temperature. The first test submarine, Kamloops, arrived in 1967.

Since then, quarter-scale submarine models with 1,680 batteries have tested everything from propellers to toilet pumps, saving over $1 billion compared to full-size prototypes.

The lake has helped develop every major submarine class for decades.

The story of this underwater testing facility awaits at the Museum at the Brig in Farragut State Park.

This Deep Lake Creates Perfect Conditions for Submarine Testing

Lake Pend Oreille in northern Idaho drops down 1,150 feet to a flat, muddy bottom. Below 100 feet, the lake stays at a chilly 39 degrees all year.

Tall trees and mountains block outside noise, creating a natural sound barrier.

The southern part has almost no underwater currents, giving the Navy near-perfect testing conditions. The lake works just like the open ocean for sound testing, but in a spot the Navy can easily reach.

The Navy Kept a Small Piece of Paradise for Secret Work

After World War II ended, the Navy closed Farragut Naval Training Station in 1946 but kept 30 acres at Bayview on the southern shore. Navy engineers checked the lake and realized they found something special.

The deep, quiet waters offered the perfect spot to test submarine sounds without going to sea. The Navy set up the Acoustic Research Detachment in the 1960s and started making submarines quieter.

From shore, the facility looks small but hides cutting-edge technology underwater.

A Strange Visitor Arrived from the East Coast

The first test submarine, Kamloops, showed up in 1967 after traveling from Maryland. Navy engineers used it to test water flow around submarine hulls, check strength, and measure vibrations.

The Kamloops helped the team create methods to record underwater sounds.

This test vessel started Lake Pend Oreille’s role in shaping America’s submarine fleet and keeping sailors safe underwater.

Tiny Submarines Pack Big Technology

Rather than testing full-sized submarines, the facility builds quarter-scale and one-third-scale models that work like the real thing. These unmanned mini-subs run on their own across the lake.

Each model carries 1,680 batteries to power its systems during tests. Using these scaled-down versions saves the Navy billions compared to building full-size prototypes.

A complete Virginia-class submarine costs about $3 billion, while these test models give the same data for much less.

The Lake Bottom Listens to Every Sound

Navy engineers turned the lake floor into a high-tech listening post with 158 underwater microphones spread across the testing range. These pick up even the tiniest sounds from test submarines passing overhead.

The system also includes 36 sound makers on the lake bottom that create specific sound patterns for testing.

Most testing happens at night when boat traffic stops and the lake gets quiet, helping engineers collect clean data.

Sturgeon Subs Got Quieter Thanks to Idaho Tests

Sturgeon-class submarines became the first major vessels to benefit from Lake Pend Oreille testing in the 1960s and 70s. Engineers worked on making these Cold War workhorses nearly silent underwater.

The lake facility tested many propeller designs, looking for shapes that moved water with less noise. Tests also checked how water flowed around the hull at different speeds.

The improvements from Idaho testing gave American submarines an edge against Soviet sub-hunters during tense underwater games.

Seawolf Brought Revolutionary Hull Designs to the Water

Navy engineers used Lake Pend Oreille to test Seawolf-class submarines with their big leap forward in stealth technology.

The unusual hull shape needed lots of testing to confirm its sound benefits before spending money on the design. Propulsion systems went through many versions in the lake to find the quietest setup.

The data from these Idaho tests helped justify the higher cost of these advanced submarines. Only three Seawolf subs were built, but the testing shaped all future designs.

Virginia-Class Subs Benefited from Budget-Friendly Testing

The Virginia-class submarine program relied heavily on Lake Pend Oreille testing for its modular construction approach.

Each $3 billion submarine has sections built in different shipyards, then put together like building blocks. Scale models in Idaho helped engineers quiet pumps, motors, and machinery throughout the vessel.

The lake facility let the Navy try various setups before picking final designs, saving time and money. This testing helped the Virginia-class program stay on budget while delivering top submarines.

Columbia-Class Missile Submarines Tested in Idaho Waters

The newest ballistic missile submarines, the Columbia-class, spent time as scale models in Lake Pend Oreille before construction started.

These submarines will carry nuclear weapons and must stay completely hidden while on patrol. Tests focused on creating super-quiet operation, with close attention to the new propulsion system.

The scale models in Idaho helped check complex computer predictions about how these massive submarines would perform. This data helped engineers improve designs before building these $10+ billion vessels.

A Billion Dollars Saved in a Remote Idaho Lake

The Acoustic Research Detachment has saved the Navy over $1 billion in development costs since it opened.

Rear Admiral Edmund Giambastiani once called Lake Pend Oreille “the submarine force’s most important body of water.”

Every major submarine class since the 1960s has passed through testing here, including Sturgeon, Los Angeles, Seawolf, Virginia, and Columbia-class submarines.

The facility continues to support American submarine superiority worldwide from its quiet corner of northern Idaho.

Local residents often spot the occasional scale model submarine being transported on the highway, a rare glimpse of the secret work that happens beneath their lake.

Visiting Lake Pend Oreille,Idaho

You can learn about the Navy’s secret submarine testing at the Museum at the Brig, 33964 N. Main Avenue in Bayview.

It’s open Memorial Day through Labor Day, 10am-4pm Sunday-Thursday and 10am-5pm Friday-Saturday. Lake Pend Oreille Cruises offers boat tours with submarine testing information.

The actual Navy facility stays secure, but they sometimes announce public open houses through local media. Farragut State Park surrounds the area with lake views.

This article was created with AI assistance and human editing.

Read more from this brand:

• How a 988-ton monster machine from New York created Idaho’s strangest landscape
• The story of Gowen Field, where B-17s once blackened Idaho skies
• How sand dunes in Idaho are helping us understand Mars