Weeki Wachee

Let me start by giving a quick background on my closed circuit rebreather experience. I started learning to dive rebreathers back in 1993 with Dr. Bill Stone's CIS Lunar MK 4. Then in 1998 the MK 5 came out and I spent a lot of time diving the unit, especially during the Wakulla 2 project. The dives got progressively longer as time went on and each of us began to get more comfortable with the rebreathers. By the end of the project, the dives were five hours of bottom time at 300 feet followed by 5 hours of decompression in the cave. At the 100 foot decompress stop, the mission divers would dismount the rebreathers and climb into a transfer bell. Once closed up, the bell would be hoisted by a cable up to the surface where it would be mated with a deco chamber already pressurized to 100 ft. The divers would take off all the wet gear and put on dry clothing and continued the deco process for another 10 hours...

Since the Wakulla 2 project, I have logged a lot of rebreather hours all over the world from Antarctica to Mexico to South Africa and the Bahamas.

Now a quick history of Weeki Wachee Springs:

It was sixty years ago that swimmers started to do underwater ballet shows in Weeki Wachee Springs located in Spring Hill, Florida. In the 1940's an underwater observation theater was built for tourists to come and see the girls with mermaid tails. The spring is so deep that the bottom has never been found. Each day, more than 117 million gallons of clear, fresh 72-degree water bubbles up out of subterranean caverns. Deep in the spring, the surge of the current is so strong that it can knock a scuba diver’s mask off. The basin of the spring is 100 feet wide with limestone sides and there, where the mermaids swim, 16 to 20 feet below the surface, the current runs a strong five miles an hour. It’s quite a feat for a mermaid to stay in one place in such a current. The Weeki Wachee River winds its way 12 miles to the Gulf of Mexico.

By the late 1960's, a few divers had tried to see what was in the bottom of the spring vent. By the 1970's, several of us cave divers made futile attempts. In 1974, the visibility went bad for a period of time and the mermaid shows were cancelled. For the first time, a group of cave divers were invited to see if we could locate the source of the spring. The best we could do swimming against the flow was a depth of 160 feet. I still remember getting to a flat rock at that depth and peering down to 195 feet at the white sand in what looked like a room. As I stretched my neck to get a better view, the current ripped my mask off. Quickly grabbing it, I was expelled not so gingerly as the current caught my underside. There was simply too much water coming out for us to go much further.

In 1980 West Central Florida experienced a severe drought. The flow at Weeki slowed down and four divers managed to get in during the night when no one was watching. Sheck Exley was one of the divers and he put in around 400 feet of line; half to the right of the entrance and the other half to the left. The flow was still very strong. One of the other divers that night was Steve Straatsma, who today is the Dive Rite Territory Rep for the Southeast United States. Steve will tell you that his exit from the cave was out of control just like everyone else as we were all blown out due to the unbelievable flow. However, as Steve exited, he was relieved of all his clipped on gear, including his primary light!

No one returned to the first room until the drought of 2000. In June of that year, Scott Pulliam, Bill Lester and I managed to get in wearing twin, steel 104 tanks. We explored Sheck's line before it was time to leave. I tried to get in again the next day with my big CIS Lunar MK 5. I got to 160 feet again and the force of the flow was collapsing the breathing bags, leaving me gasping for breath. I called the dive and was already devising modification for another attempt when the word came that no more diving was permitted.

Now, seven years later, another drought is upon us. The flow in Weeki Wachee has been reduced to record lows. Karst Underwater Research, a non profit diving group, headed by Jeff Peterson of Tampa, put together a team and a diving plan for Weeki Wachee. Permission was granted and diving started in the spring of 2007. I was delighted to be invited and I joined the group with a big smile. On May 23, 2007, I dove Weeki wearing twin 104's with minimal effort because the flow was so low compared to what I remembered. It was obvious, however, that rebreathers would be needed to swim any distance. I did a test dive to see if the O2ptima rebreather was up to the challenge. It was. The effort to get in was still very tough on me, but I got in. So we planned our first big dive with two steel 85's for bailout, a bottom mix of 8/70, two scooters each and two more emergency tanks left just inside the cave. We already had proper bailout along the ascent line with richer mix up to 100% oxygen at 20 feet.

The team began diving after hours so as to not interfere with the mermaid show. Support divers went first to set up our dive, including placing scooters at 195 feet.

It is June 29th, 2007 and the entry time is 17:43. I am diving with Brett Hemphill. He is on his rebreather and I follow with my O2ptima rebreather. Again it is a fight to get in, but I do it. I was a bit winded, but by the time I clip on my Trimix bailout and the two scooters I regain my breathing rhythm. Now I am following Brett and the cave curves down through a smaller area where there was once a massive breakdown with boulders the size of homes piled up everywhere. The room gets deeper and bigger. We reach the end of the line Brett had put in on an earlier dive and drop the first scooter. Brett hooks on with his knotted reel and I follow for 300 feet or so. We get to a big boulder and the cave seems to go big in both directions. I elect to go right and Brett goes left. We had agreed to do this if we felt good about the dive, plus not knowing when the drought would end which will make the flow increase, time for exploration is of the essence. So I went my way and installed and surveyed 1170 feet.

Brett laid 1200 feet plus the first 300 we did as a team. I had more turns then he did so my bottom time ran over the two hours we had planned for. He had fewer turns so he was out first. Not seeing me, he assumed I was out. As soon as I realized the clock was approaching the two hour mark, I finished the survey and raced toward the exit. As I approach, I could hear the music from the underwater sound systems the mermaids use for the show. My bottom time was 2 hours 20 minutes... and I was still at 210 feet! My Hammerhead gave me a two minute decompression at 210. Then again at 200 feet and so on. The 170 stop is right at the place (173 feet) where all that water surges through an opening the size of a door. I did the best I could to stay there. The 160 foot stop was impossible. It was done at 153 instead. The rest of the deco went well.

I had plenty of bailout gas with me so I decided to see just how far I could go on the Extendair scrubber cartridge. Beside I was just laying there motionless for hours in 74°F (23°C) water, not exerting much energy so I knew the time for the cartridge could be extended. But how much? The Hammerhead computer was doing its job and I did my deco. Finally I got to the 20 foot stop. The mermaids have an underwater staging area below the visible stage and it is an air bell measuring maybe 5 feet wide and 12 feet long. There you can stand up and be out of the water from the waist up. We can talk, eat or sing along with the music. I propped myself onto a seat and just breathed from the loop, maintaining a 1.4 PPO2. I felt that if I had a cartridge breakthrough, I was in the perfect place to experience it. I was in an air bell and had lots of pure, open circuit O2 with me to finish out my deco obligation. Plus, I had Brett with me, too. Finally the Hammerhead cleared so I surfaced. The time was 03:11 in the morning on June 30th, 2007.

Brett told stories of being in a part of the cave with a bottom so deep it could not be seen. So we plan a return trip on July 14th, 2007 using a similar plan as before. This time, we were joined by rebreather diver Corey Mearns of High Springs. Brett had a video camera and a big light. Off we went to the end of his line, passing what looked liked soda straw formations and fragile stalagmites. There we dropped our extra bailout tanks and first scooters. Down we went to the deep section to see what was there. Brett ran the line high across a very large dome room. Corey stayed in mid water. I went to the floor to look at a small possible lead. It was low and small.... perhaps an opportunity on another dive. We motored back to the main tunnel. The dip before going up turned out to be the deepest, showing 407 feet on my Nitek Plus (set in gauge mode). Once back in the large tunnel we headed down the larger section perhaps 90 degrees from the deep area where we had just been. We cruised at a depth of 325 feet, spooled off another 400 feet and tied off the line in the middle of a great passage with more tunnel going ahead.

Reluctantly, we all decided it was time to go back... and face the long deco. My Hammerhead was right on the job. The bottom time was 125 minutes and the deco was eight hours. I did the last two hours on open circuit with pure O2 in the mermaid air bell. The support team was great. They had all the gear out before my 30 foot stop. These dives could not be done without their help, period. Thanks a whole lot to all of you!

Paul Heinerth