The exploration of Main Drain: Utah's deepest cave

Tony Grove Lake on a clear summer day in the mountains of northern Utah

(Drew Michael Hill, Shutterstock)

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Estimated read time: 7-8 minutes

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Editor's note: This article is a general information piece. The Main Drain Cave is dangerous and should only be explored by experts.

LOGAN — Cache County's Logan Canyon is a unique place.

Peter Sinks, a natural limestone sinkhole in the area, regularly records some of the lowest temperatures in the 48 contiguous states. Naomi Peak is the highest point in the Bear River mountain range. One of the oldest living trees — the Jardine Juniper — is found in the canyon, and Logan River is home to one of the best naturally reproducing cutthroat trout populations in Utah.

Another lesser known fascinating feature of Logan Canyon is the number of caves found in the Tony Grove area.

In 2016, Kristen Bahr, a graduate student at Utah State University, compiled a thesis on the geology of the karst landscape in the Tony Grove region. In her theses, she indicates that cavers have found more than 100 alpine caves between Tony Grove and White Pine lakes, making this area one of the highest concentrations of caves or karst features west of the Mississippi River. According to Bahr, these caves range from 5 meters (approximately 16 feet) to 374 meters (approximately 1,227 feet) deep.

Main Drain Cave discovery and exploration

Main Drain Cave is found in the Tony Grove area. It holds the distinction of Utah's deepest cave, at 1,227 feet in depth, and 4th longest cave at 2.02 miles, according to

Official credit for the discovery of the opening and first 260 feet of the cave is given to Thomas Haskett in 2000, even though there is some speculation that others had previously repelled into the first pit chamber. Because The Tony Grove area has many vertical caves and pits, there is confusion on what the cave was first called. Early on, the cave was named Deception Cave or pit by Haskett because there was confusion on whether it was Lucifer's Lair, another pit cave in the area with similar features.

The Tony Grove Project, in 2003, had local cavers Peter Hartley, Jon Jasper, Brandon Kowallis, David and Ryan Shurtz, Lance Dickey and others look for and map as many caves and pits as possible within the Tony Grove region. It was during this exploration project that Ryan Shurtz discovered a small tunnel about 60 feet off the floor of Deception Cave. This opening led into more large pits — a few horizontal slots — and the amazing discovery of what is now the deepest cave in Utah. Ryan Shurtz is credited with the breakthrough discovery.

After subsequent trips into the cave and using cartographic techniques and measuring methods the cave name was changed to Main Drain. It is called Main Drain because it is suspected that almost all groundwater and snowmelt from the many caves and pits in the Tony Grove area eventually run through some portion of Main Drain Cave or have some connectivity to it.

Scientists have used fluorescein, a red powder that turns fluorescent green when wet, to trace groundwater flow in the area. The fluorescein was dropped into areas where streams, snowmelt and groundwater enter underground. Traces of the dye were picked up by receptors in Main Drain Cave and in many of the springs in Logan Canyon, according to the exploration group. Amazingly, the dye traveled underground as far away as 6 miles down the canyon at Wood Camp Spring, which is approximately 3,000 feet below the elevation entrance of Main Drain Cave.

Exploration is ongoing. Dave Shurtz is credited with most of the cartography effort. Cavers have reached what they thought was the bottom when they found a terminal lake or sump. Divers have taken scuba equipment to the bottom lake and exploration indicates that the cave could possibly be even deeper.

Geological features that make Main Drain Cave possible

Geologists and earth scientists studying the Tony Grove area call much of the rock in this area dolomite. Specific names, such as Fish Haven and Laketown dolomite are given to help delineate the area and tie its unique properties to surrounding areas.

Laketown and Fish Haven dolomite is similar to limestone, which is soluble with rainwater and snowmelt that picks up and carries carbon dioxide from the air and soil. This water, which now contains carbonic acid can, through time, dissolve certain rock types such as Laketown dolomite. With the possible aid of earthquakes, geologic time, and gravity, carbonic water will eat away at the dolomite, travel through cracks, fractures and fissures and produce the large pits, narrow slots and passages we call karst landscapes and solution caves.

Professionals and experts only

Caves like Main Drain should be accessed by professionals and experts. They are just too dangerous for the weekend or casual caver.

Most of the caves in the Tony Grove area are known as pit caves. This means that they are more vertical than horizontal. You need to be an expert in rappelling and being able to climb back out on a rope to enter most of these caves.

Regular rock-climbing gear is not sufficient; specialized rappelling and climbing gear are required. Main Drain Cave is a very dangerous cave with drops off well over 200 feet. The rocks are jagged and sharp and can cut through the standard rock-climbing rope.

According to those who have been there, the cave air temperature is around 38 degrees Fahrenheit; the cave waters a degree or two colder. Cavers who do go down need to be prepared for the cold as hypothermia is a real possibility. The cave has dripping water, running water, waterfalls, snow, slippery rocks and darkness, which is why the pros wear proper clothing and footwear for the wet and cold conditions.

Time is also a factor. Those who have been in Main Drain estimate that it is a 12- to 14-hour adventure. Cavers describe the experience in Main Drain as "brutal." The amount of time and energy to explore Main Drain is not for the weak of heart or body — and, as mentioned, is for the experts and professionals only.

Cave locations

It is actually against the law to give out GPS coordinates for certain cave locations. Under U.S. Code Title 16, Chapter 63, the Federal Cave Resources Protection Act of 1988, information concerning the specific location of any significant cave shall not be made available to the public.

This code is to protect the caves from vandalism and overuse. It also protects sensitive wildlife like certain species of bats from getting sicknesses. Plus, it protects the general public from mishaps which could cause serious injury or death.

Individuals interested in caves and caving can join the National Speleological Society (NSS), or a local cavers club. The NSS has up-to-date information about caves and caving around the country. Active local clubs allow interested individuals to share information and experiences and possibly organize outings.

Future exploration

In 2013, local cave diving experts Josh and Michael Thornton, owners of Dive Addicts in Draper, accomplished the demanding task of taking scuba diving gear into the depths of Main Drain with the assistance of local caver Peter Hartley. They reached the terminal sump, and the Thornton brothers rigged with scuba gear dove 66 feet and surfaced in a room, said Michael Thornton.

The Thornton's made a second attempt the following year to find deeper passages but encountered problems with higher water and water clarity. It was too dangerous to continue and the effort was thwarted, Michael Thornton said. The Thornton's believe Main Drain Cave could have another passage that would take it deeper.

The gear was left at the bottom and plans to revisit the cave to dive and explore are still an option in the future, Michael Thornton said. When asked what it is that drives a person to enter these dangerous caves and to dive them, Thornton said it is really just an exploration bug. The excitement of exploring places where few have been, or where no human has been before, and to discover what is there is the main factor.

In 2016, cavers from Utah, Colorado and Texas entered Main Drain Cave with scuba gear. Jean Kreja and David Moore made a dive in the terminal sump and went 79 feet deep and surfaced in a passage that lead to another terminal sump. A description of their adventure into Main Drain and a video of the dive can be found on explorer Adam Haydock's blog.


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