Bob Thomas’ Terrifying Descent into Darkness: The Tilly Foster Cave Nightmare

Bob Thomas’ Terrifying Descent into Darkness: The Tilly Foster Cave Nightmare
Incident LocationDiver Full Name
New York, Brewster, Tilly Foster caveBob Thomas

In the small town of Southeast, nestled within Putnam County, New York, exists a flooded pit that plunges an astonishing 600 feet into the Earth. This well-kept secret amongst divers has a history of both individuals and items vanishing into its depths, never to re-emerge. Located on private property, the current owners have no interest in diving nor wish the liability of having divers on site.

Beyond its tranquil facade lies the tragic tale of experienced technical diver Bob Thomas, whose momentary lapse in judgment led to a fatal outcome in its unforgiving depths. This is the Tilly Foster cave diving disaster of 2017.

Meet Bob Thomas

Bob Thomas diver

Meet 48-year-old Bob Thomas from Jersey City. Always one for adventure, he joined the Navy in 1987 and served until 1993. Following his service, Bob pursued higher education and obtained his master’s degree from the University of Buffalo.

His professional journey led him to the field of IT, where he had been thriving ever since, most recently working as an Enterprise architect for Major League Baseball in New York City. Outside of work, Bob’s life had been enriched with remarkable achievements. He scaled mountain summits, indulged in rock climbing for years, and for the past 15 years, he’d been a very active scuba diver, achieving the rank of Master Scuba Diver in 2013.

Exploration Begins

Experienced diver Dan Wright was notified of a deep flooded mine near Brewster, New York, the intrigue being too much to bear. Dan found himself compelled to persuade the owners to allow him and a team, which included Bob, to explore the mine, map it out, and provide legally binding waivers to release them from exposure to lawsuits in the case of diver injury. It took some time, but by Spring of 2014, the team was granted permission.

Upon the first survey of the site, they found it was more picturesque than any of the images sent to them on internet searches. It was very large, 300 feet by 400 feet across, resembling a small lake with sheer cliffs surrounded by foliage. Evidently, there was a diving academy of some sort there at one time, as indicated by the sturdy steel stairwell and steel dive platform on pontoons still in great shape.

The Deepest Dive Site

The mine’s waters were spring-fed, with some flow, the destination of which was yet unknown. It is the deepest dive site in the tri-state area outside of the ocean. From the jump, it drops 177 feet right off the platform, meaning there is no shallow end.

The mine was not merely a deep, featureless hole; there were multiple horizontal tunnels or drifts, as miners called them, starting at 300 feet. Some extended for hundreds of feet until the tunnel played out, while others covered only short distances. These passageways were meticulously carved out during the late 1870s to the 1880s, coinciding with the latter stages of the mining operations.

History of the Mine

The mine was named for Tilly Foster, who bought the land that the mine was on from George Beal. After Foster’s death in 1842, the property passed through several hands before coming into the possession of Harvey Island Steel Company. The mine opened in 1853, employing large numbers of Irish and Italian immigrant workers, known by numbers rather than names due to the difficulty of pronouncing their names. The mine reached its peak of production in the 1870s, being 600 feet deep and employing 300 miners who produced 7,000 tons of ore per month.

In 1887 to 1889, the mine was made into an open pit, a process that took two years and made it the largest open pit operation in the world at the time. Tragically, in 1895, a major collapse killed 13 miners, leading to the mine’s closure in 1897 due to financial difficulties.

All equipment was removed, and the property was closed off to dumping around World War II. The site gained notoriety as a body dumping ground for the mob for nearly 50 years, with various items and vehicles being thrown into the mine.

The Tragic Dive

On November 19th, 2017, following four years of the mine’s exploration, the team reached the site to commence a sequence of exploratory dives to search for Robin Murphy, a female murdered in 1995 at the age of 17 and dumped in the mine. Bob opted to dive without a buddy on this occasion and entered the mine alone around 12 pm. Unfortunately, before he even started the dive, he had low gas supply onset and no reserve in case of an emergency.

Bob dove to a depth of 171 feet to the bottom of the flooded mine shaft. The water temperature rapidly dropped from 70 degrees on the surface to a chilling 42 degrees only 10 feet down. Below 40 feet, it remained at 42 degrees. The water contained a significant amount of particulate matter, reducing visibility drastically. Bob required a heated wetsuit to endure the frigid conditions, but the suit’s battery could only sustain the heating for approximately 90 minutes.

A Desperate Situation

Amid the chilling temperatures and unsettling darkness, Bob became disoriented underwater, and his dive quickly spiraled into disaster as he became entangled in massive wires and cables. Bob ran out of air at 12:34 PM, very close to this as analyzed from his Shearwater dive computer, which takes samples every 10 seconds. His fellow team member, Dan Wright, started his dive at 1 PM, exploring some distance away from Bob. Dan had no idea that Bob was in a dire situation or dead at this point.

By the time Dan surfaced at 2 PM, Bob was long gone. Bob’s girlfriend contacted the sheriff’s office around 3:50 PM, concerned that he was late for a party at her house. Police went to the mine and found the team members, who explained that Bob was late surfacing from his dive, giving his air supply. Dan Wright, when questioned by the police about not calling 911, explained that they intended to return the following morning with additional equipment to search for Bob in the water.

Tragic Conclusion

State Police divers, in collaboration with Brewster and Mayopack Falls fire departments, initiated a search of the mine. They employed sonar equipment to aid in locating Bob’s body. Tragically, his body was located and retrieved around 1 PM on the day following his disappearance.

In July 2018, the Putnam County Sheriff’s Department officially closed the case, attributing it to a tragic accident. In September 2018, a stone memorial marker was engraved and erected by some dedicated members of the exploration project as a tribute to Bob.

May Bob rest in peace. He is remembered as an upbeat man whose passion was helping people and diving. A few dedicated men continue diving the deep flooded mine to this day, but many do just a single dive and never return.



How deep is the Tilly Foster cave?

The Tilly Foster cave is a staggering 600 feet deep.

What happened to diver Bob Thomas?

Bob Thomas tragically ran out of air and became entangled in wires during a dive, resulting in his death.

Why is the Tilly Foster cave famous?

The cave is famous for its history of divers and items vanishing into its depths, as well as its dark and chilling underwater environment.

Patrick Broin
Patrik, a seasoned cave diver, shares his first-hand experiences and expert insights on the treacherous world of cave diving accidents.
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