Manatee Springs Exploration

[Editor's note: the following essay was originally published in 1994 and appears in different forms across the Internet. Since the publication of the article, Jablonski has set new records -- over 19,000 feet at an average of 280 feet deep--at Wakulla Springs]

Manatee Springs Exploration Sets a New North American Record

By Jarrod Jablonski

Manatee Springs Regains Her Stature as North America's Longest Submerged Cave System

On June 6, 1994 Todd Kincaid and Jarrod Jablonski marshaled a great deal of support, borrowed some ambition and explored an additional 800' of siphon tunnel located within the cave system at Manatee Springs Park, Florida. This dive, which required nearly nine hours of submersion and measureless support, concluded at 11,074', establishing a new North American record.

The simplicity with which this was related doesn't begin to do credit to the numerous people and arduous hours logged within the years of this project's existence. To truly credit the numerous divers that have challenged Manatee's interior would be impossible. However, this article will attempt to recap the years of exploration and research that has set Manatee Springs apart as North America's longest underwater cave.


Manatee Springs is located in Manatee State Park roughly six miles WNW of Chiefland, FL. Manatee Springs is located on the Manatee Springs Quadrangle in SW 1/4, SE 1/4, sec. 26, T. 11 S., R. 14 E. All five openings (four of which are passable to cave divers) occur along a fracture zone trending in a SW direction approximately 1800' from Manatee Springs to Friedman's Sink.

The Beginning

Catfish HotelMany years of cave diving legends have assaulted Manatee's interior and all were met with a raging flow and limited visibility. Manatee is a first magnitude spring with an average discharge of 181cfs (nearly 120 mgd). The daunting force of this flow coupled with the early years of undependable scooters made early exploration a monumental undertaking. Cave diving experts like John Harper, Bob Friedman, Court Smith, Sheck Exley, John Zumrick, Bill Main and Bill Gavin all battled against these challenging conditions. Sheck Exley was perhaps the most consistent contributor to these efforts and found himself obsessed with the multitude of Manatee's secrets. The author was fortunate to have known and dove with Sheck and thereby gained some information from the storehouse of history within his mind. Within this article I will review and try to answer some of the questions Sheck strove to conquer during his many years of exploration within Manatee Springs.

Early Exploration 1961 - 1981

Manatee Springs does in fact have an interesting history of exploration. For example, the first recorded traverse between two submerged cave entrances was completed from Manatee Springs to Catfish Hotel as early as January 1961. As with many of the local cave systems Sheck Exley played a crucial role in the evolution of thought and action within the Manatee system. Sheck discovered Friedman's Sink (named for his friend and co-explorer Bob Friedman) in March 1973. The sink was at this time merely a solution pipe a few scant inches in diameter. Lewis Holtzendorff then located this hole on the surface and the team began an excavation that many of us today take quite for granted. Although small, this roughly 3-foot diameter opening remains the farthest upstream entrance and is therefore a valuable exploratory and research aid.

During the years to follow, numerous dives were conducted within the Manatee Springs cave system extending the breadth of knowledge and cave available for scrutiny. On May, 1975 Exley, Holtzendorff and Smith dramatically extended the volume of explored passage by nearly 1300', quite an accomplishment for the time and technology. The exploration terminated at nearly 4,000' and continued to support the assumption that Manatee Springs predominately consists of one major trunk passage with parallel meanders that return back to the main tunnel.

The late 70s and early 80s found Manatee Springs on center stage vying for the world's longest underwater cave. Once again, Exley and company were at the forefront of these long push dives into the raging depths of Manatee Springs. In August 1981 Exley and Pitcairn extended Manatee out to a total penetration of 7,667' where they reached an impenetrable restriction. Later that year Bill Main and Bill Gavin were to follow another route from that of Exley and extend Manatee's penetration to nearly 7,800'. Manatee Springs was to remain the world's longest underwater cave for another seven years until Exley's mammoth dive in Chips Hole in which he extended the record out to over 10,000'.

Exploration 1990 - 1994

Manatee Springs, the site of so many years of scrutiny and hours of bottom time, was soon forgotten leaving many of her secrets shrouded within her raging depths. However, old habits die hard and January of 1990 found Jerry Messick and Jarrod Jablonski once again probing the mysteries of Manatee's interior.

An attempt to refine some long penetration techniques and some general curiosity found these divers rekindling the light within Manatee's long forgotten corridors. It had been nearly nine years since light had touched these surfaces and at nearly 8,000' one could gain a true perspective on the tenacity that allowed those long swimming penetrations so many years earlier.

Following a review of both Exley/Pitcarin and Main/Gavin's lines, the duo began their exit. During the long trek out, the team noticed a large siphon tunnel at approximately 6,000' and returned two days later for closer review. Immediately upon entering the large siphon tunnel it became apparent that this would become quite a discovery. The main tunnel, which is fairly smal,l with a floor-to-ceiling height of 5' and a diameter of roughly 6', suddenly balloons to more than three times that size. Following the exploration of nearly 1,500' of this new lead the flow conditions became even more adverse and the exploration was postponed in favor of more favorable conditions in other regions of the system.

Messick and Jablonski took advantage of a lower flow period in March, 1991, to search for other promising leads. The divers were suspicious about the lack of flow present near the end of the upstream passage. It became apparent the earlier teams must have missed the main flow (a feat easy to do on a nearly 8,000' swimming penetration of Manatee Springs). Hopefully the improved scooter technology would make a closer look more feasible and reel more passable cave. Once again Manatee responded with an astounding surprise. While the team searched the main corridor, Messick found a small lead that broke into a large cave passage. The next several dives revealed more than three thousand feet of remarkable cave before the increasing flow and the decreasing size of the tunnel called for a recess in the exploration efforts.

The nature of the Manatee dives obviously called for some significant logistical considerations. Both divers relied heavily on the clean Hogarthian style that was developed by Bill Main and refined by Bill Gavin. In addition large 95 stage bottles were used in some sections of the cave to reduce the number of bottles necessary. The distance traveled also required the staging of scooters via a system designed by Lamar English and George Irvine. Once the silt had cleared, Messick and Jablonski had reached a total penetration of more than 10,000'.

The Next Assault

A review of the past dives and future exploratory plans forced the team to reconsider the safety of the main line present within Manatee Springs. Long-time cave diving friends Todd Kincaid, Sherwood Schille, Casey Mc Kinlay and George Irvine joined the exploration efforts and it was decided to remove the mass of multiple threads that had heretofore passed as a main line and replace them with one continuous line. Lamar Hires was contacted and he made arrangements for the NSS-CDS to donate some line for this project. The removal of the tangled mass of lines (in some places, as many as four main lines) required nearly a dozen dives and a great deal of patience. It was also decided to place line arrows with distance markers throughout the cave to facilitate the logistics of research and exploration dives.

The group agreed that a more refined and scientific approach to the exploration was called for and it was decided to manage Manatee's exploration during poor Woodville Karst Plain Project (W.K.P.P.) Tallahassee exploration. The group began to amass as much information as possible on the particular nature of Manatee's structure, striving to expand the breadth of knowledge as well as the extent of cave passage.

The first goal the team tackled was to explore the relationship of the large siphon tunnel discovered by Messick and Jablonski. The advent of Bill Gavin's superscooters, which were well-tested in the depths of Tallahassee, greatly facilitated this project. The group has found from experience that most dives of significant range must be as effective as possible, often with multiple tasks being conducted on each dive. Every dive done must not only accomplish some task, but should in some way facilitate the following dive. A team of dedicated divers can in this way accomplish nearly any task.

In March of 1994, George Irvine and Casey Mc Kinlay began the series of dives that would allow maximum efficiency in the teams newest project. Their upstream trek to the 6,000' siphon tunnel was designed stage and safety bottles for a later push dive. Running efficiently, they managed to accomplish all their objectives and still find time to push through a restriction at 7,500', exploring an additional 900' of cave passage. Their report was promising and the group readied itself for a series of challenging dives.

While the team prepared for the next assault, numerous logistical considerations began to become apparent. The large siphon tunnel was located beyond 6,000' and necessitated the negotiation of roughly 2,000' of of restricted cave, making air and scooters more difficult to transport. In addition, the cave repressed efficient travel with a powerful flow that repelled one's efforts for the spring tunnel portion and inhaled divers in an uneasy inflow for the second leg of the long journey. Furthermore, while the siphon tunnel had continued beyond the original restriction encountered by Messick and Jablonski, it continued to intersect numerous sections of cave collapse, creating an impediment to both efficiency and safety. Air calculations also demanded astute care while confronting a raging siphon that begins at over 6,000'.

With the safety considerations in place and the dive plan well-orchestrated, the team began the siphon tunnel pushes. Todd Kincaid and Jarrod Jablonski began the pushes by leapfrogging through the cave on bottles placed on previous setup dives. The divers retrieved the full bottles placed at 7,500' by Irvine and Mc Kinlay on the previous push. The full bottles were then brought to the end of the current line and left for either emergency air or the next push. Thanks to careful planning, efficient ravel and perhaps a bit of luck the push went well and the team explored nearly 1,500' of new siphon tunnel without incident.

The dives began to increase in complexity as the siphon flow was greater than anticipated and became a noticeable impediment to efficient exit. The cave was very brittle forcing a diver to take on a daunting flow unaided by pulling techniques. In addition, the cave continued its tendency of intersecting paleosink debris which greatly impeded the team's progress. As if to further complicate matters, the siphon tunnel visibility rapidly began to decline as other tunnels high in particulate content intersected the siphon tunnels path.

The cave flow continued to increase as the region's lower surface water content slowly removed its shackles. With increased flow, the dives magnified in complexity and bottom time. The average depth of 90' made Manatee an excellent Nitrox dive, greatly enhancing the team's safety and efficiency. Yet as the dives increased in complexity and cumulative dive time, the team began to become more concerned about CNS toxicity. Decompression sickness was considered to be far more favorable than the incapacitating effects of a seizure, yet the bottom times now in excess of 200 minutes certainly called for some relief. George Irvine contacted Dr. Bill Hamilton, W.K.P.P.'s most frequent source of physiological information, who helped construct dive profiles to reduce toxicity risk. Technical advice was also gained from the generous assistance of Arnold Jackson (American Underwater Lighting).

Armed with this new information the team decided on one last push before the flow became unmanageable. Again Kincaid and Jablonski began a push made possible by his dedicated team. Our usual group of divers was then joined by cave divers Tyler Moon, Bill Mee, Pat Hare and Barry Miller who all provided assistance and support. With all stage bottles in place Kincaid and Jablonski began the last push of the season and were immediately met with a daunting flow and settled in for a long dive. At the siphon tunnel the duo were already nearly 30 minutes behind schedule and not even at the halfway mark. Nearly 120 minutes of penetration later, they finally reached the end of the current line and began the exploration, choosing to survey as the exploration continued. The cave almost immediately hit a long section of significant debris and continued to increase in flow while becoming much lower and wider. The cave passage became relatively undefined and exploration was further slowed. As the team worked through restriction after restriction in now less than 10' of visibility, they reached the end of available penetration air and began the arduous exit. At 11,074' the team had established a new North American record, yet the hardest part still remained.

Immediately upon turning, the team ran into a zero visibility restriction that seemed impassable. Common sense won out over appearances and the exit would continue to be slow with a flow not soon to be forgotten. Furthermore, the duo had decided to try and remove all equipment from the cave to prevent any further equipment damage in the aggressive Manatee water. In retrospect, this violation of the group's policy was a poor decision and proved to be costly. Laden with six stage bottles and three scooters each, the exit was all but efficient. People often pay when policies are violated and this penalty would be a day of submersion.

As the distant glow of the exit became evident, the bottom time crept toward 300 minutes. Nearly nine hours later the two divers again breathed the sweet air of open space and made necessary apologies to the support crew who made all this possible. Joining our other valuable members were John Denizmen, Kendal Fountain and Richard Hisert, all geologists of true character and incredible patience. As we exited the park, two hungry, prune-looking divers, I thought of Sheck Exley and his many years of contribution. I wished that he were around to call and review the dive with and, most of all, to compare notes on this labyrinth of daunting surprises called Manatee Springs.

Future Assaults

As the exploration of Manatee Springs continues and more of her secrets are revealed, our group is determined to learn as much as is possible about this mysterious cave. One of the questions Sheck strove to answer revolved around the classification of Manatee Springs. Is Manatee an exsurgence fed almost entirely by seepage waters from the surrounding karst or is it a resurgence supplied by the sinking of surface streams? Manatee Springs certainly resists simply classification. For example, it has no apparent sinking streams in the general vicinity, nor does local rainfall seem to immediately impact the spring flow, leading one to classify it as an exsurgence. However, Manatee does retain a high discharge and is predominately composed of a single trunk of impressive penetration, indicating a possible resurgence.

In truth, Manatee is probably a cave of multiple identities. While the data remains under evaluation, it appears that the cave may pass under the Waccassaa River Drainage Basin and shows the Suwannee to be pirating another river's drainage basin (a concept considered by Exley as early as 1976). The tremendous extent of the large siphon tunnel trending directly for the Suwannee river may be the primary route of this pirated water as it discharges into the Suwannee River. This tunnel may help to explain the high particulate content within Manatee's water and the consistent existence and nature of the tunnels on the southeast side of the corridor. The presence of Long Pond and other surface features may also indicate the possibility of an old karst lineament preferentially draining the area. The lack of surface input on the west side may explain the clearer, less extensive tunnels located therein and help to produce some of the signs of exsurgence dominated cave systems.

Furthermore, the apparently high organic content of the Manatee water is of particular interest when one considers the recent pollution problems present within the region's water supply. The nearby trailer park is fighting a battle against a polluted water supply with the source still in question. Several sources may be considered, yet it is conceivable that Manatee's conduit system plays some role in these local problems. Future research will hopefully include water quality tests and sediment samples.

In addition, several of the passages under exploration contain numerous mammalian remains of questionable age and origin. It is highly unlikely that the remains were brought in from the nearest known exit, roughly 10,000' away. The numerous collapse features coupled with the frequent impassable sinkholes within Manatee Park make it likely that some of these sinks were at one time passable. Future attempts will be made to video these artifacts and gain a better understanding of their origin. The remains await the learned knowledge of a very serious cave diving anthropologist. Know any?


This long journey has taken us back to the gargantuan efforts of Manatee's early explorers through the evolution of technology and penetration technique and back to the ancient remains of some long ago stray mammals. It has been an extended journey that will continue as long as there is cave in which to wonder how things were and how they yet might be. The secrets of Manatee Springs have, to be sure, only begun to come to light. As we slowly edge forward pushing back the blackness with our feeble sphere of light, let us hope that we can maintain the reason and intellect to safely continue our quest.