Hi
Lake sump is a good one as well in Peak. You can bypass it if you hate it when you get through and its got a good line in it.
Hope this doesnt come across as condescending but I wrote the below for our club newsletter. It's based on my very limited experience of freediving in caves (Rowten, Lake sump, swildons). Some more experienced cavers may take issue with some of it but it works for me.......
Freediving for wallies?. (PS NOT AIMED AT THE OP - JUST THE TITLE OF WHAT I WROTE!)
A few people have made comment to me about doing some freedives in order to do some more interesting trips. I am by no means an expert (in fact I am the above mentioned wally), however I am pretty happy in the water coming from a diving back ground, but thought I would jot down a few thoughts about it in case anyone is interested. I am sure most of you are more than aware of the following, but in case anyone isn?t:
? It?s a really good idea to speak to someone who has done a freediveable sump before and not just jump on in.
? Neoprene ? You don?t want to be swimming around in a fleece suit for any period of time, especially if there?s a lot of caving to be done beyond. Lake sump in Peak is OK, as it?s very short, but as most can attest ? it?s very cold. Wear a wetsuit, the thickness won?t matter much, and you won?t get as cold. Cold makes you gasp and breathe shallow which is not what you need when freediving!
? Temperature ? Diving straight in to cold water will be a shock. Don?t do it. Roll around in the sump pool first so your body gets used to the temperature ? it won?t be fun, but it will make the dive more relaxing. Those who saw me rolling around in Swildon?s sump 1 pool like a beached whale will recognise this technique.
? Wear a hood ? The difference a neoprene hood makes is amazing. When diving the other day, I had pulled my hood down on the way out of a cave when I decided to have a little dip in a section of canal. I almost bounced off the water when my head touched it, it was so much colder. It also keeps water out of your ears and almost isolates your face from the water which can be a source of stress for some. Also works well in ducks I find.
? Mask ? Being able to see where you are going, see airspaces etc is very useful. Sometimes you can?t see much but I do find it less stressful when I can see. Also, a proper mask seals your snozz, so you can?t get water up it; which is a bonus.
? Weight ? Whatever you are wearing you are going to be buoyant / floaty especially as you are holding your breath. This can cause issues as you are fighting to keep yourself off the roof of sumps; this is annoying and slow and finding yourself clattering off the cave can be a bit stressful. Normal diving weights can ne threaded onto a caving belt easily; a couple of Kg should do. Or put some rocks in your pockets ? seriously. Also try and get all the air out of your suit before you swim.
? The rope ? Most (all?) freediveable sumps will have a line through them. They are usually straightforward so the line is only tied at the start and end of the sump. NEVER let go of the line and NEVER clip yourself to it in any way. Just go hand over hand, head down so you don?t clatter your lid. Personally I like to do them face down, but often you will find yourself rolling onto your back. Wearing a mask this isn?t an issue as it keeps water out of the nose, but I would suggest you tuck your chin down. This keeps your mask away from the ceiling as they can be banged and fill with water (easily fixable but not when holding your breath!).
? Slowly slowly catchy monkey ? Rushing freedives is not going to end well, you can bang your head, wedge yourself, miss airbells etc, Get comfortable wearing a mask, be warm and slow down and relax. It will be easier.
? Bad air ? One cautionary note about ?bad air?. Some airbells between free dives are small (like an upside down bath) and therefore can get a build-up of Carbon Dioxide in them. Never hang around in small airbells; get in, orientate yourself, clear your mask, and move on. It?s an incredibly low risk but worth being aware of.
? Hyperventilating ? A bit contentious this one. Your urge to breathe comes not from a lack of Oxygen but from a build-up of Carbon Dioxide. If you breathe deeply a couple / 3 times, fully inhaling and flushing out your lungs, you can remove any residual Carbon Dioxide, this means when you take a final breath and dive in, you won?t get that burning urge to breathe as soon, meaning you can hold your breath longer. There are a couple of issues with this, BUT if you only do it a couple of times you will be fine.
(I will expand on the last point here - you can black out if you do the above and hold your breath for a long time but over the average sump length you should be OK. I am not here to advise anyone the above are just my thoughts caveat caveat caveat blah blah blah waffle waffle.
Matt