Zacaton. A History

Zacaton is the deepest of five ceynotes located on a large ranch, El Rancho Asufrosa, in northeastern Mexico. It was "discovered" on a reconnaissance trip made at the end of two weeks of exploration and surveying in the Nacimiento Santa Clara, a cave system at the base of the El Abra near the Nacimiento Mante. The exploratory team, led by Jim Bowden, laid more than 1400 ft. of line in the Santa Clara, but had ceased their efforts due to the depths encountered in the distant reaches of the cave. More than 1100 ft. back, depths exceeded 250 ft. At that time, 1989, the team was not routinely exploying mixed gas techniques in their exploratory efforts in Mexico. The door to the Santa Clara was temporarily "closed." Jim had studied geological survey and topographical maps which revealed the possibility of inland "ceynotes" in the Karst terrain found at the southern extreme of the Sierra de Tamaulipas.

On a ranch near the small town of Aldama, five ceynotes of variable size and character were located. Exclusive entry and permission to dive was granted by the owner and in late April 1990, exploration began. The ceynotes proved to be extremely unusual. They are aligned generally east to west within a radius of approximately two miles. They are highly sulfurous in odor, in one named Poza Asufrosa, the sulfur precipitates and floats on the surface in raft-like formations. The waters discolor and tarnish all metalk. They seem to leech the surface of galvanized tanks. The systems are surprisingly warm, 93 degrees in Poza La Pilita, 87 degrees in Zacaton, 86 degrees in Poza Caracol, 87 degrees in Poza Asufrosa, and a cooler 83 degrees in the huge oasis-like Poza Verde. Unlike the others, the waters in Poza Verde are layered in thermoclines and behave more as a lake in times of flood and drought and seem less responsive to the changes imposed by the water table.

The exploratory team began the systematic exploration of the ceynotes. Initial efforts were concentrated in Poza La Pita. This 68 ft. by 120 ft. ceynote is the warmest of the five at 93 degrees F. The surrounding walls reveal tufa formations often associated with warm thermal springs. The side walls are coated with a dense algae which hangs like curious stalactites. Measurements made using the ScubaPro personal sonar device revealed a system that enlarges significantly with increasing depths. At 150 ft., La Pita is 396 ft. from north to south and 239 ft. from east to west. The team initiated the search for a connection to the ceynotes located immediately to the east or west, however, no ongoing passsage was found in the early exploration.

The depth of La Pilita was plumbed to 360 ft. and dives were made to 250 ft. On May 2, 1990 divers Jim Bowden and Gary Walten entered the Nacimiento at the western boundary of the ranch. The river is formed by the spring run emanating from Zacation. A typical "boil" was noted on the water's surface near a limestone outcropping. Pursuing this current, the divers located a small cave and followed a northeast azimuth until they had exhausted the line on their reel. With passage obviously continuing, they turned the dive, obtained an additional exploratory reel, returned to their tie-off and resumed laying line.

Now in the lead, Gary soon noticed a bottle green glow ahead. He covered his light and confirmed a natural light source that could mean but one thing, they had made a connection toi the surface. The exuberant divers emerged into Zacaton at a depth of 26 ft. and surface in the beautiful ceynote which takes its name from the islands of tall grass, zacate, which float across its surface. The succeeding days were spent surveying the nearly 600 ft. of passage (named El Pasaje de Tortuga Muerte for the frequently encountered turtle skeletons) connecting the Nacimiento and Zacaton and recording baseline information on this impressive system. The surface of Zacaton is approximately 70 ft. below the surrounding land. It is 380 ft. in diameter and roughly circular. Its lateral walls undulate and the system dimensions increase with increasing depth.

A rough survey has been completed to 175 ft. of depth from the center of the ceynote using the ScubaPro personal sonar device. It is hoped that side scanning sonar techniques can be applied in the future to study the full extent of this ceynote which is now known to exceed 1080 ft. of depth. The depth recorded for Zacaton in 1990 was erroneously measured at 250 ft. when divers Gary Walten and Ann Kristovich dropped the weighted plumb line onto a prominent ledge which projects markedly into the ceynote at 230 - 250 ft.

Exploration continued on the ranch in August 1990 with dives by Karen Hohle and Ann Kristovich in Poza Verde. This tropical oasis is greater than 600 ft. across, somewhat cooler than the other ceynotes and surprisingly shallow, a mere 140 ft. by our measurements in four quadrants. Jim and Gary sought passage in Poza Asufrosa with side mount configurations, but the tight passage choked off after 30 ft. of penetration.

Caracol, like her immediate neighbor, Zacaton, sits beneath a cliff face. To date only one dive has been made in this cave by Jim, but he observed large going passage on an azimuth that would lead to Zacaton. The maximum depth in this system is not known as the passage travels beneath the cliff and could not be adequately measured by plumbed line. The maximum depth on Jim's dive was 72 ft.

After this early exciting start, members of the Proyecto de Buceo Espeleologico Mexico y America Central spent the next two and one-half years exploring cave systems associated with the inland Blue Hole of Belize. Solo efforts by Jim from 1987 to 1988 had resulted in the connection of St. Hermann's Cave with Petroglyph Cave and the inland Blue Hole. The 1990, 1991 efforts of the team added more than 1500 ft. of water-filled passage to the survey and discovered a previously unknown and spectacular pit in the jungle. Dives made in the downstream Boiling Hole follow an azimuth which will likely result in a connection to the Actun Tah system. Work was halted in Belize in 1992.

The "Proyecto" resumed the exploration of the five ranch ceynotes in April 1993, fully equipped with mixed gas capabilities to allow the safer exploration of the deeper systems. Sheck Exley joined the team for a week and with Jim dove the previously unexplored depths. La Pilita revealed at greater than 358 ft. of depth, going passage to the southwest. Zacaton, however, revealed the greatest surprise. On air dives to 258 ft. by Jim and 407 ft. by Sheck, no bottom was in sight. The previously plumbed depth of 250 ft. was proven to be an error! The divers dove beyond the ledge which had captured the measured line in pursuit of the elusive bottom. The following day Jim, Sheck and Ann returned to Zacaton to attempt a more accurate plumb. The line spun off the reel, past 500 ft., past 800 ft., past 1000 ft! The weight finally stopped after some 1080 ft. had been measured. The line was secured to the north wall of the ceynote and the divers completed plans to make a deep mixed gas dive the following day.

In April 1993 Jim dove to 504 ffw. and Sheck to 721 ffw. Tables for both divese were prepared using Dr. X. software. Neither diver experienced any performance difficulties or physiological complications during or after the dives. These two would be the first of seven sub-500 ft. dives made in Zacaton in a 12-month period. As the week of diving came to an end, Sheck and Jim agreed to return together to Zacaton and, like Hillary and Norkay, pursue the exploration of the depths of this upside down Everest. The apparent perfect sight for an open circuit dive to 1000 ft and beyond had at last been found. It was warm, there was no perceptible current, the natives were friendly and access to the system was uncomplicated.

The goal was thus declared that within the calendar year a dive to obtain the bottom of Zacaton would be made by Jim and Sheck. Members of the Proyecto made six trips to Mexico during the ensuing 12 months. With each return, Jim dove progressively deeper in order to prepare himself for the 1000 ft. attempt. Sheck meanwhile pursued the exploration of a huge underwater cave at Bushmansgat, South Africa, diving to 863 ft. in this system. During this dive, Sheck experienced visual, somatic and neurological symptoms of HPNS. The symptoms resolved during his ascent to his first deco stop at 400 ffw. and there were no persistent effects.

In September Jim dove to 744 ft. Team member Kristovich dove to 554 ft., setting a new women's depth record with this effort. On December 2, 1993 Jim made a dive in excess of 800 ft. The exact depth could not be documented as all three of the digital depth gauges he was wearing ceased to function at various depths ranging from 684 ft. to 756 ft. Jim, however, had visually noted the 825 ft. marker on the descent line before reversing the direction of his dive. Jim experienced multiple joint DCI upon the completion of his decompressin obligation. Symptoms resolved following aggressive hydration, oxygen therapy and in water recompression. There were no persistent symptoms.

The 1000 ft. attempt had been slated for December 25, however it was the consensus of the team in early December that the conditions imposed by the unusually wet rainy season were unfavorable for such an effort. The current in El Pasaje de Tortuga Muerte was fierce and imposed a very undesirable heavy exertion dive prior to any deep attempt. It was necessary to traverse this nearly 600 ft. of linear cave passage prior to any dive in Zacaton, making all of the deep dives in fact repetitive dives. For the safety of the divers, the dive was rescheduled for April 1994.

In April 1994 the Proyecto, including Sheck and Mary Ellen Echjoff, assembled on the Rancho Asufrosa. Two days were spent staging the required decompression bottles at their specified depths in Zacaton and El Nacimiento. The dive would be accomplished on independent descent lines, a condition both divers favored to avoid contact and potential interference during the very rapid descent. Each effort would be solo by necessity. Sheck would use Heliair 6.4. Their tables were similar and were formulated utilizing Dr. X. software. Both divers carried an assortment of tables since the exact time of descent, bottom time and the maximum depth of the dive was uknown. Both Jim and Sheck made multiple deep air acclimation dives to prepare themselves for the 1000 ft. attempt. Early in the morning on April 6, 1994 all was felt to be in readiness and the divers and their support eam assembled on the banks of El Nacimiento. Jim and Sheck geared up and swam together through "El Pasaje" and into Zacaton. The pre-dive mood was positive and optimistic.

The men began their descent at approximately 9:50 a.m. central standard time. Jim dove to 925 ft. and would spend nine+ hours decompressing. Sheck, for reasons we will probably never know, failed to return from his dive. He had reached a maximum depth of 906 ft. During the 12 months spent in training and preparation for the deep dives, the following dives were made by members of the Proyecto de Buceo Espeleologico Mexico y America Central:

              50 - 100'             197
             101 - 200'              22
             201 - 300'              39
             301 - 400'              48
             401 - 500'               3
             501+                     7

Of significance is that these 316 dives were accomplished in only 51 diving days. Jim is credited with more than 100 of these dives, including four of the sub-500 ft. efforts, and a dive to 411 ffw on air.

The Proyecto will continue its efforts in Mexico after a brief pause for the rainy season. Jim feels certain after reaching 925 ffw that a dive to 1000 ffw is possible and he will pursue his plans to see the bottom of Zacaton. With the use of Heliair, the survey of the distant passage of the Nacimiento Santa Clara will be resumed. The exploratory team also plans to aggressively explore the magnificent deep caves of the Sierra Madre Oriental, including the Rio Choy, Rio Frio, Rio Sabinos, Nacimiento Mante, Nacimiento Huichihuayan and many others.