Let’s face it: air has gone out of style. For just about any type of dive (with the possible exception of checking out the drain at the deep end of the pool), air is neither the preferred nor optimal choice of breathing gas. For dives to moderate depths and for repetitive dives, nitrox is the ticket. For deep dives, tri-mix (in various percentages), accompanied by nitrox and oxygen for deco, is the norm for all serious divers. Did you ever wonder how all this got started? Well, here’s the story.

Prior to late 1987, everything was done on air. The two noted exceptions were Smith and Holtzendorff in 1975 and Sweet in 1980. Both of these dives were done on heli-ox. Diving was air diving; there was no mixing or analyzing gas percentages, no custom, computer-generated tables—heck, we didn’t even have digital depth gauges, much less dive computers! We had air and the Navy tables, period. We did, however, use oxygen for deco on dives deeper than 250’ for an extra safety margin. My first dive with Bill Gavin was at Sally Ward, where we swam downstream (accompanied by Bill Main) into the second big room and then took a quick look at the upstream. Our dive profile was 31 minutes at 240’. This was just a “normal” dive for us at that time.

The exceptional visibility and white walls of this cave system were just begging for further exploration. The problem was that the cave had been pushed about as far as possible while swimming. To lay some line, we needed scooters that could easily handle 300’ depths. Our scooters, the old Tekna DV3X’s, were only good to 160’. A few days after our dive, I called Gavin with an idea: “If we can equalize the pressures inside and outside the scooters with some kind of automatic depth compensating system, we’ll be good to go.” Bill’s reply was not what I expected, but it was good!

“Mine’s about half finished. Come over this weekend and I’ll show you how to do it.”

Now we’re getting somewhere! Bill told me what parts to get, and he showed me what to do. In a nutshell, all the sealed internal compartments, even the individual battery cells, were vented. A demand regulator supplied gas from an attached pony tank upon descent, and a Viking exhaust valve released the expanding gas upon ascent. Brilliant! The pony bottle was filled with nitrogen in case there was a spark from the motor. Spark + oxygen + hydrogen = “KABLOOEY!” (I like the word “kablooey”—it has character. “Catastrophic spontaneous disassembly” is the NASA equivalent of “kablooey.”) In any event, Gavin chamber tested his scooter to 340’, and as one would expect, it worked flawlessly. Next came in-the-water testing: Madison Blue, Alachua Sink, and finally, a trip to the Super Room in Eagle’s Nest. With all systems go, it’s time to go see Sally.

On August 17, 1987, we’re back at Sally Ward. This time my role is to set up Bill and Bill. I was to put their stages, scooters, and oxygen bottles just inside the restriction so that they would not have to waste time and energy fighting their way through 40 yards of chest-deep eel grass. However, things did not go as planned from the start. First, I couldn’t find the spring; I wound up in the blind hole that looks just like the spring except it has no cave. After much searching, I finally found the spring, and after a few trips, I got everything in place. Next, the visibility was down to only 30’. On the dive, when Bill and Bill dropped the stage tanks at the far side of the second room, Gavin left the line reel clipped to the stage. Then the cave went deep—the line ended at 270’; the tunnel, too small in which to scooter, continued on at 290’. Bill and Bill parked the scooters, and Gavin began laying line from his spool, swimming at what Bill Main would later describe as “an impressive rate, given the depth.” The cave was low and silty, and before long, Main started having “depth issues.” What kind of depth issues? Let’s just say that his silt technique and mental acuity were compromised to the extent that he momentarily swam off the line into a total silt-out. To say the least, this was not your average, everyday dive. The extreme depth, the exertion of swimming, along with the poor visibility and the fact that he was in a wetsuit and chilled, were all significant factors that contributed to Bill’s problems. Bill and Bill laid 170’ of line, swimming at 290’. By the time they made it back to the scooters at 270’, Bill’s issues had cleared up considerably, and the ride out was uneventful. The dive was 35 minutes at 290’. Later that night, Bill Main declared, “We have got to start diving gas,” and that was the last of the exploration dives, on air, in Sally Ward.

The next Saturday night, Bill and Bill were back again; this time, their 104’s contained 550 psi of helium topped off with air to 3600. This was the first dive on tri-mix. (I declined the invite: I didn’t think it sounded like a good place for three divers; besides, I had my eyes on the upstream.) There were no tables for tri-mix, so Gavin carefully analyzed the Navy heli-ox tables and the air tables and extrapolated a schedule of tables for deco. (He had also made an O2 analyzer and tested their mix before the dive.) They laid another couple hundred feet of line. The following were some of Gavin’s log book notes from the dive:

Downstream, added line. Seems to end in a big room, but there must be a small tunnel here somewhere—or was the flow lost earlier? Fifty foot vis. Scooters perfect at 290’. Weird stomach/skin bend? Stomach area swollen and sore. Not serious but very strange—helium? Relatively clear at depth. Used separate bottle to fill dry suit. Forty minutes at 290’. Deco: 80’-4, 70’-6, 60’-9, 50’-15, 40’-17 (air) 30’-34, 20’-51, 10’-90 (oxygen)

We waited three weeks for the visibility to improve before we set out to explore the upstream. This time was spent planning, checking gear, making up new tables (Gavin spent considerable time on this), and mixing gas. I remember my dad coming by when I had a helium tank hooked up to my 104’s, along with my back-up regulator and pressure gauge, to monitor the fill.

“What are you doin’?” he asked.
“Mixin’ up some helium”, I replied.
“You goin’ to do some underwater weldin’?”
“Nooo, I’m gonna breathe it.”
“Why?”

I took a breath of helium and blurted out, “We’re goin’ deep; we’re off to see the Wizaaard!!” (classic munchkin voice). It was too funny; I burst out in ridiculous munchkin laughter until I was crying. My dad left, slowly shaking his head and saying, “There’s somethin’ bad wrong with y’all; bad wrong.”

On September 14, we pulled up at the culvert, with our windows down, and turned the van off. We listened closely for the sound of a vehicle; not hearing anything, Bill Main said, “Let’s do it.” With that, we sprang into action. The doors flew open, and we quickly unloaded the van; in two minutes flat, we had neatly arranged three sets of 104’s, stages, O2 bottles, and scooters down by the water (practice makes perfect). We left and got suited up. Bill dropped Gavin and me off and soon joined us. We geared up and made our way through the eel grass to the spring. We rested briefly, and then descended to the entrance.

One by one, we squeezed through the restriction: Main first, Gavin next, and then me. We dropped the O2 bottles at 30’, gave a quick OK, and were off, motoring along, breathing our stages. Down the pit we went, then into the corkscrew, and in no time, we were at the balcony. We left the stages, gave a nod, and were off again. The visibility was well over 150.’ Main motored straight ahead for a few seconds and then gracefully went into a left turn/barrel-roll nose dive that had him heading straight down. A couple of seconds later, when Gavin reached that spot, he did an exact carbon copy of Bill’s move. (That was cool—it was kind of like an underwater dog fight with scooters instead of F-14’s). Seconds later, when it was my turn, I did one, too. (Not that anyone was looking; it just seemed like the thing to do.) When my roll-turn was complete, we were all lined up, heading straight for the upstream. 150’, 200’, 250’—I hit the inflator on my BC and held it down. We leveled out at 285’, keeping an eye on the line which ran along the right wall near the floor. (Sheck Exley and Dana Turner had put this line in 13 years prior.) After traveling approximately 150’, Bill stopped and held his light on the tie-off. As Gavin zoomed in and tied off the reel, I looked at my watch: seven minutes.

Seven minutes from the surface to the end of the line. Ahead was borehole virgin tunnel, going straight away, as far as I could see. Full tanks, scooters, and clear as a bell at 290’! Is this good or what? When Gavin pushed off from that rock, I couldn’t help but grin as he leveled his scooter and pointed into the cave, “GO.” As soon as Main saw the signal, he was off. The plan was for Main to be in front, scouting out leads, followed by Gavin laying the line, and I was to make the wraps (not textbook procedure, but very efficient). We were spaced about twenty feet apart, and the view from my perspective was spectacular. As we motored along, the beams from Main’s and Gavin’s lights slowly swept from side to side, methodically illuminating every square inch of the tunnel. I occasionally made a quick wrap to secure the line, and had just gotten into a good rhythm, when all of a sudden, they both stopped. Their slow sweeping light movements were replaced by much sharper “where did it go?” flashes of light. The cave went vertical, so we started swimming up. At 230’ the cave appeared to end in an unstable breakdown area. Gavin tied off the line and we left a little note to “The US Deep Cave Diving Team.” We all shook hands and then motored away. We ended up adding over 200’ of line, as this excerpt from Gavin’s log book indicates:

Added 220’ feet of line. GOOD DIVE—Strange to be in tunnel this deep and be clear-headed. Gas mix = 600 psi; topped to 3400 with air. Deco = 7@ 140, 0, 3, 5, 5, 5, 10, 10, 15, 20, 20, 35, 50, 70 (air from 110’-40’; O2 from 30’-10’)

As we reached the old end of the line, I couldn’t help but think of Exley and Turner. Sheck had to exit solo; Dana never made it out of the tunnel--Hell of a place to die. For us, though, the dive was a monumental success: narcosis was gone and none of us suffered any DCS symptoms, the scooters were flawless, and the big unknown didn’t come kill us all. It appeared we were on to something with this tri-mix stuff.

Our next dive was, literally, just around the corner and was to be an epic adventure: the king of all sneak dives, Wakulla Springs.