Missouri Adventures: An Introduction to Bonne Terre Mine
Our first “real” dive as new, inexperienced divers.
My brother and I became open water scuba diving certified in September 2020. For various reasons, we wanted to ease our way into ever-larger scuba diving trips. So we decided our first “real” dive would be at Bonne Terre Mine, in Bonne Terre, Missouri. If you are unfamiliar with Bonne Terre, no worries. I was, too, until Peter sent me a link. I think it may be Missouri’s best-kept secret for dive enthusiasts.
Bonne Terre Mine is a historic deep-earth lead mine founded in 1860. For 102 years, this mine was the world’s largest producer of lead until it closed in 1962. During its operational years, massive pumps kept water cleared out of the mine. Once mining operations ceased, several pumps shut off, allowing water to creep in, creating a one billion gallon, seventeen-mile long lake.
It’s the perfect playground for scuba divers of all experience levels, with calm waters and a constant 60-degree water temperature. 500,000 watts of stadium lighting mounted to the cavern roof illuminate the upper layers of the lake. The water is crystal clear, natural spring water, with visibility of up to 100 feet. Remnants of the old mine equipment lay submerged on the floor of the mine. Although there is a lack of aquatic life, the mining equipment is fascinating and how could you ever be bored diving through history and geology?
Let’s dive into Bonne Terre!
Diving takes place on the weekends at Bonne Terre Mine, so we got up bright and early on Saturday to head to the mine and situate our rental gear. Since we were new divers, we did not own any of our own gear. It turns out, even if you do own your own gear, it’s easier to rent weights from West End Diving (the company which runs the scuba tours), as you won’t have to carry your own weights down into the cavern with you along with your other gear. West End’s weights live on the diving dock at the edge of the lake. Renting gear was easy and convenient, and upon our arrival at the dive shop we tried on the gear the shop laid out for us.
Since the mine water is only 60 degrees, divers must wear a 7mm wetsuit. In addition to the 7mm wetsuit, they recommend a thick dive hood (ours were 6mm). I did wear 6mm gloves on the first dive but quickly ditched them for the second dive for my comfort. I had difficulties with my buoyancy and I believe my gloves were impeding my ability to manipulate the inflate and deflate buttons on the low-pressure power inflator.
After we obtained and dressed in our gear, we sat down with the other members of our group and the divemaster to go over the briefing and procedures for the mine. The briefing covered how we would enter the mine, getting our weights down on the dive dock, checking our Nitrox to ensure mixture percentage, how we would enter the water, and the dive routes we would explore during our time in the mine. The divemaster also explained that after we made our giant stride into the water, we would perform a weight check, demonstrate mask clearing and emergency air sharing skills, and then head over to the shallow bowl to begin the first dive. With the formalities of the briefing out of the way, we picked up our gear and began the march into the bowels of the earth.
We entered through the old Mule Entrance, which had a musty and moist aroma rather like a rainforest. As we trudged into the depths, our guide Brandon pointed out features of the mine to us, including an area where plants are grown under grow lights. Brandon pointed out that they never water the plants; the plants survive on the relative humidity of the mine. We passed by a number of massive pillars, some stabilized by ginormous metal bands, until we finally arrived at the dive dock.
Preparing for the first dive.
We set our things down on the provided benches then went to analyze our Nitrox tanks and gather our weights. Both Peter and I completed our Nitrox certifications on this trip. Prior to leaving for the trip, we completed the online portion of our Nitrox certifications and just needed to complete the practical portion of the certs. Brandon showed and taught us about the Oxygen analyzer and we measured the Oxygen percentage of each of the tanks while under the supervision of the instructor and the diver assigned to the tank. We recorded the tank number, our names, and the MOD of our tanks in West End’s record book. We took our analyzed and recorded tanks back to our spots on the dive dock and began to assemble our gear.
After we performed a buddy check on each other, we were ready to jump in. I inflated my BCD, held my goggles and regulator securely, and took a giant stride into the cool water. I cleared the space in front of the dock and Peter followed me in. We performed our weight checks then proceeded to swim to the shallow bowl. The shallow bowl is a plateau where the bottom of the mine is only 30 feet below the surface. I used a buoy line to descend slowly so I could equalize my sensitive ears. After each diver reached an appropriate depth, the dive master and safety divers checked the divers’ skills.
I had loads of trouble with my buoyancy on this first dive. At first, my diving was fine. At some point, however, I floated back to the surface where I met the surface attendant (the surface attendant follows the group in a kayak). Katie, one of the safety divers, came up with me. After discussing the dangers of floating up like that, she could see I was becoming frustrated with my diving. She gave me some tips and the surface monitor gave me some extra weight to help keep me down. After this, I was able to stay down with the rest of the group, see the submerged mine cart, and complete the dive. During the surface interval, I asked for more pointers from Katie. Every diver and member of this dive team was very understanding and helpful. I very much appreciated their assistance as a brand new diver.
Get ready for round two!
After an hour-long surface interval above ground, it was time to go back into the mine. During the break, we ate some lunch and I looked up more buoyancy tips on the Scubaboard forums. Dive number 2 is not as deep a dive, with the entirety of the dive at 40 feet or shallower. This allowed me to keep a visual on the bottom, which in turn aided my buoyancy.
I still inflated and deflated my BCD quite a bit, so the safety diver signaled for me to surface. They clipped 3 more pounds to my BCD. The safety divers did keep signaling tips to me in the water, and the divemaster, Brandon, came over to me and illustrated to me that I ought to spread eagle over the terrain and let all of the air out of my BCD. At one point, safety diver Katie added a rock to my pocket for extra weight (I got to keep the rock!). She also showed me to use my breathing and movement to keep from moving up and down in the water column.
I enjoyed the second dive much more than the first simply because I was able to stay at depth and with the group. We dove through the keyhole and around The Structure, which is an old mine lift. I also was able to stay right near Peter, so it was nice to know where my dive buddy was.
The adventure comes to an end.
We took a very short surface interval on the dive docks before heading into our third dive of the day. We got fresh tanks between every dive, and this was no exception. With our gear on our fresh tank, we dived right in. In order to dive the trails, the divers must first swim or snorkel to the “trailhead”. At first, the adrenaline of my first official dive pushed me through, but as the day wore on the swimming became more tedious and tiresome. At this point, I felt a wee bit tired.
On this third dive, we headed to a portion of the mine where the Styrofoam from the blast caps floated up against the roof of a passage. We also saw the smoke room and some of the deeper parts of the mine. I surfaced about 15 minutes before the official end of the dive at the dock. I became too tired to continue on underwater, so I snorkeled back to the dock along the surface with the kayak attendant. Overall, it was an awesome experience and we can’t wait to go back and collect more trails.
Bonne Terre isn’t just for divers.
Don’t worry. Even if you’re not a scuba diver, you can still tour this behemoth mine. The mine features walking tours of the top two levels via the old mule tracks and a boat tour. There’s still plenty to see above-water, too. The walking and boat tour features the No. 1 elevator (which you also see on the underwater trail), submerged ore carts, wrapped pillars, and the abandoned overhead cat walks, which hang 50-100 feet above the lake.
Divers may lodge at the Bonne Terre Depot Bed and Breakfast, however, my brother and I did not. We opted for the Holiday Inn Express and Suites just fifteen minutes up the road from Bonne Terre in Farmington. We planned to be up for breakfast, anyway, so the additional drive time did not bother us any. Part of why we decided on Holiday Inn Express was because they offer a warm buffet-style breakfast and the Depot does not. Overall, this is a trip I would highly recommend if you are a diver itching to get diving and you don’t live near the ocean. It’s definitely an ideal introduction to scuba diving.
