Freediving at the SETT

I'd never really seen the point of freediving, thinking it was just the preserve of people without access to scuba equipment. That was until we had a couple of French freedivers come out on the boat with us. While swimming round Chumpon pinnacle at 25m, these guys would drop down to the bottom, hang out for what seemed like minutes but was probably only seconds, then break for the surface. I didn't show it in front of my clients, but I was secretly impressed.

A few years ago I learnt about a local woman who had started teaching freediving courses in Porstmouth, at a place called the SETT. It turns out that SETT stands for "submarine escape training tank" and it's this huge, 10 story building that houses one of the deepest tanks in Europe. During the week, submariners don safety equipment, jump in an airlock, and practice escaping a downed sub from 30m. At the weekend, they rent it out to a company called Deeper Blue, who teaches freediving courses there.

I read about one of these courses in a dive mag and it sounded fun. I'd had it at the back of my mind for a while now, so when a space because available at short notice, I jumped at the chance.

Walking off the ferry from Portsmouth to Gossport, you could see the SETT towering over all the other buildings in the area. Wandering towards the naval base I couldn't help thinking how tall the place looked, and imagining what it would be like looking over the rim and into the waters below. I didn't have to wait for long as.

After a quick safety briefing, 8 eager students filed into the lift and up to the tenth floor to check out the SETT. Looking into the abyss below filled me with a mixture of excitement and dread. I've been to 30m plenty of times, but always with a tank on my back. Looking into the murky depths, you could barely see the bottom, let alone imagine yourself swimming down there and back on a single breath. I decided at that point that I'd be happy to hit 15m, and anything more was a bonus.

The two days fell into a natural routine. You'd start with a classroom session where you'd learn more about the theory and practice of freediving. Being a scuba instructor, much of this was familiar to me. However it also reminded me how much I'd forgotten. You would then move onto the first pool session of the day, followed by lunch, another classroom session and then the final pool session.

The first pool session started with a static apnea warm-up on the surface. This involved "breathing up" to make sure you were relaxed and had enough air in your system, and then simply holding your breath with your face in the water. I started at 1min 30sec and then 2min. On the second tank session I did 2min 30 sec, and by the end of the weekend I reckon I could have pushed it to 3min.

Next we practised our pulldowns, which as the name would suggest, involved us holding our breaths and pulling ourselves down to a fixed depth. The whole point of the day was to start building up our confidence, so I did a quick pull-down to 5m and then a couple more to 10m. After lunch we increased this to 15m, and by the end of the day I was managing pull downs to 20m.

After warming up on the second say with a static and a moderately deep pull-down, we graduated to the freediving fins. Known as constant weight freediving, this discipline involved swimming down to depth and back again without the assistance of a rope. The fins allowed you to get down and back much faster. However, because you were expending more energy and building up more CO2, it became increasingly difficult to hold your breath.

I did a couple of 10m practice dives, before heading for 15m. Unfortunately the increased speed of decent, combined with the previous days diving and my less than expert technique started to take a toll on my eardrums. Equalisation had become increasingly difficult, to the point where it was downright uncomfortable. I eventually made it back down to 20m, but knew that the elusive 25m mark was beyond my bruised and battered eardrums. I don't normally have equalisation problems, so felt that by body had let me down a little. However I felt confident that I had the lung capacity to hit 25m and possibly even 30m once I'd had chance to rest my ears.

Apart from equalisation problems, my biggest issue was unlearning techniques that have become second nature from diving. Things like exhaling on ascent or body positioning in the water. So I definitely head back to the SETT to work on my technique and aim for the bottom of the tank. I may even consider a freediving holiday to Egypt at some stage.

Form more info on freediving at the SETT, check out some of these links.

• "The SETT facility":http://www.royal-navy.mod.uk/server/show/nav.3097
• "Deeper Blue":http://www.deeperblue.net/courses/sett/
• "Emma Farrell":http://www.emma-freediver.co.uk/courses.html
• "An article about the course":http://www.cdnn.info/news/industry/i050604.html
• "Video of the SETT on YouTube":http://www.youtube.com/watch?v=-z4PV4SxstU
• "Photos of the SETT on flickr":http://www.flickr.com/search/?q=sett%20freediving&w=all