A Most Unusual Dive Site: Bonne Terre Mine

After a fun filled summer of diving in the UK, my partner CJ and I decided to head back to the USA to spend the autumn (fall, for us colonials) hiking and camping in some of the national parks out west. Of course, being avid divers, we couldn’t pass up the opportunity to do a few dives as well!

We started our adventures in St. Louis, Missouri. It’s an excellent base partly due to the huge numbers of micro breweries and excellent eating establishments, and partly as this is where my family are based and so they get nominated to be the designated drivers to and from the tap rooms… However beer and pizza aside, Missouri also boasts some great hardwood forested state parks in which we have been gaining some hiking fitness and also a pretty unique dive site in an old lead mine, Bonne Terre Mine. It is known as a different and interesting dive site so we headed an hour south of St Louis, for three dives there on a Saturday.

Bonne Terre Mine is only open to divers on weekends and provides accommodation and diving packages for those traveling long distances, or not fond of early morning starts. There are also boat trips through the mine offered for any non divers – see www.bonneterremine.com. The mine is a national historic site; the earliest shaft was dug in 1864 and it was once the world’s largest producer of lead ore. Mining continued until 1962, when the pumps that kept the water out were turned off, forming the 17 mile long underground “Billion Gallon Lake”. For fans of Jacques Cousteau, he filmed here in 1983.

The air temperature in Bonne Terre is 17°C (62°F) and the water temperature 14°C (58°F) year round with over 30m (100ft) of visibility. A total of twenty-four dive trails have been laid out in the lake, taking the diver through numerous archways, around massive pillars and past abandoned mining artifacts. Depths of the dive tours average between 40 to 60 feet. Divers are toured through the mine by specially trained dive guides. Customers are not allowed to use personal dive lights in the lake, but these are not really needed due to the 500,000 watts of above-water illumination as well as the guides’ torches. For first-time visitors, all dives are lead by a dive guide and you must complete trails 1 and 2, before being allowed on any other trails. On completion you can get your dive log or a card stamped so you may do different trails on subsequent visits.

Dive 1: Trail 1

The first dive was a group checkout dive with a max depth of 15m (50ft). The dive started on a flat area at 10m, where all divers demonstrated a few basic skills such as mask clearing and an out of air drill. From there, we struck out as a group over some deeper areas of the mine, making a roughly circular loop through an area close to the entry platform. The guides were great about using their torches to point out items of interest, including an ore cart with a pickaxe that we all took turns picking up.

CJ’s thoughts:

The first dive was pretty impressive as check out dives go, the visibility is excellent and you get a real feel for the vastness around you as you swim across over deeper water. The pillars loom out of the twilight-like light and the ore carts and abandoned tools connect you with the history of the mine. It is also nice not be blinded by lots of torches, and the guides are very good at highlighting points of interest and checking on the group without shining the lights in your face.

Dive 2: Trail 2

The second dive trail penetrated slightly farther into the mine, with the group being lead through many more arches and short passageways. A highlight was swimming through the ‘opera window,’ a door-sized opening from one smaller passage into a ledge above a large open cavern. It was quite amazing to see the dark outlines of seven massive support pillars looming out of the shadows.

CJ’s thoughts:

This trail has more swim-throughs and cool sights than the first dive and the opera window is pretty incredible. Despite the trail being very good, I had a harder time relaxing on this dive due to some other divers having buoyancy issues. The guides dealt with this well, but as an instructor I always find it tough to see potential safety issues and not be the one to react! With the swim-throughs and yoyo-ing divers I found it a little more crowded on this dive despite there being the same number of divers, so this was not my favourite dive.

Dive 3: Trail 4

This dive was my favorite by far. Most of the other divers that day departed after the first two dives, so we were treated to a much smaller group, and the route for this trail included even more passageways not traversed during the basic checkout dives. We were able to swim to and through a large metal superstructure that formerly housed an ore elevator. The ceiling lights illuminated it brightly from above. The effect was very atmospheric! Another highlight was a cavern with a “cloud” formed from wisps of iron oxide. Since there are no real currents in the mine, rust from deteriorating mining equipment and tools floats gently above. This created a mesmerizing atmosphere for our group to enjoy.

CJ’s thoughts:

This trail/ dive was incredible! By far the best dive of the day and well worth the trip here. We had a smaller group for the last dive of the day and the trail took us through several really nice swim-throughs, to the elevator shaft and into a room with an eerie-looking cloudy layer, caused by the oxidising iron equipment and lack of water movement. When lit by the torch light it was quite breathtaking. This and the general beauty of the trail really made the day, I’m looking forward to returning to try out some of the other trails next time!

Both of us enjoyed the day’s diving immensely and would highly recommend a visit for a day or weekend if you find yourself in the middle of the United States.

This article was originally published by Scubaverse