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Falmouth-Cathedral Cave System

The Falmouth-Cathedral Cave System is located off Highway 90 in Suwannee County due west of Live Oak, Florida. There are several karst windows into the system as the main conduit makes its way from Cathedral Canyon Sink to Ellaville Springs on the Suwannee River. Additionally, the system has been hydrologically connected to the Edwards-Suwanneecoochee system via dye tracing. 

Exploration History

Conditions in the system have minimized the opportunities for exploration of this system over the past twenty-five years. There is an entire chapter dedicated to exploration of this system in the book Caverns Measureless to Man. Sheck Exley explored the system to a penetration of over 10,900’ in 1990, but then continued exploration was halted until 2003 due to challenges in water quality and access. Between 2003 and 2005, exploration of the system resumed, and Todd Leonard and Bjarne Knudsen pushed the exploration of Cathedral beyond 17,000’. However, years of persistent drought caused the flow to reduce to a trickle for several years, and in 2014, the NSS-CDS closed access to the property.

In the fall of 2015, KUR member Derek Ferguson noticed a photo posted to social media of Falmouth Springs. For the first time in many years it appeared that the system would be diveable and exploration may be possible.

Permits for access to both Falmouth Springs and Cathedral Canyon were granted by the Suwannee River Water Management District and the NSS-CDS, and diving operations commenced. In October 2015, KUR divers had a meeting to discuss the goals and standards for the project. KUR divers also replaced 7000’ of line beginning from the entrance in Falmouth to approximately 4500’ past Cathedral, installed safety bottle depots at 2200’, 4500’, 6000’, and 8000’, and installed a decompression habitat in Cathedral Sink.

In November and December, KUR divers began the process of exploring the system and conducting scientific research. The current end of the line is nearly 19,000’ past Cathedral, and radio location beacons have been used to validate Sheck Exley’s survey. Additionally, water and biological specimen samples and data have been collected throughout the system.

Unique Challenges

Aside from the distances posed by continued exploration in the Falmouth-Cathedral system, there are other unique challenges:
  • While the system averages approximately 150’ deep, the depths vary throughout the system from a maximum of over 185’ to as shallow as 70’. These variations in depth mean that a diver is at risk of violating a decompression ceiling or suffering a squeeze/block. Additionally, divers expend precious inflation and diluent gas with the constant depth changes.
  • Visibility in the system averages 10-20’. With a main trunk passage in excess of 40’ in width, this means that divers need to remain extremely focused or risk losing their guideline.
  • Decompression obligations. The most recent exploration dives have had bottom times in excess of 300 minutes at an average depth of 150’.


Science in Falmouth-Cathedral is being conducted by Florida A&M and the Suwannee River Water Management District. Equipment support has been provided by Dive Rite and D3 Diving/Suex.

Ken Sallot