Next month, you’ll have a chance to tour the inside the Ballard Locks’ large chamber.

On Wednesdays in March, the Army Corps of Engineers will be doing guided tours for the public. It’s part of a fundraiser for the Corps Foundation, a nonprofit that benefits the Locks.

The tours will accommodate up to 15 people at a time, starting at 10:30am each Wednesday and lasting about an hour and a half. Engineers Jon Hofstra and David Chapman will lead the tour, which will start at the Visitors Center theater with a short presentation and safety information.

The tour is not for the fainthearted — to get into the deep large chamber, participants will have to climb down a 70-foot scaffold. Then, the tour will make its way through dark tunnels with uneven footing, which could be strenuous at times.

“If you have mobility issues, fear of heights, vertigo, or claustrophobia, this is not the tour for you,” the Corps Foundation says.

They also say that airborne shellfish allergies should be considered for some.

Participants should plan to bring their own flashlights and foul-weather gear, including plenty of warm layers, rain gear, gloves, and wading boots that can be used in four inches or more of water.

To reserve a spot on one of the tours, click here. The suggested donation is $25-30, which will go towards developing educational programs at the Locks.