At the end of August I went on a lido crawl around London, where the water was about 16°C. My next swim was last Saturday (23rd October); that's almost an 8 week gap, and during that time the water temperature had dropped to 10.5°C.
The Outdoor Swimming Society have divided water temperatures into bands:
0-11 DEGREES: Freezing.
12-16 DEGREES: Fresh.
17-20 DEGREES: Summer swimming.
21 DEGREES PLUS: Warm.
30 DEGREES: Pool temperature.
Over on Facebook, Kate Rew (OSS founder) posted some similar ranges:
6 degrees and below winds you. lot of puffing getting in.
12 degrees and below - cold
above 12 degrees - different kind of experience, everyman swimming
Either way, it's fair to say that the water is now significantly colder, which explains why the lido is now closed to the general public (i.e. lack of demand). Although I didn't swim for a while, I have been gradually turning down the water temperature in my shower; as well as helping me to acclimatise, this should also save a bit of money on my gas bill! I don't know the actual temperature, but there's a neutral position with 20 notches in each direction (hot/cold) and I'm now 10 notches into the cold zone. One interesting effect is that I now find hot showers unpleasant, so when I stayed overnight elsewhere I had to turn the shower down to 1½/10.
Even with these preparations, the water still felt very cold. During the summer, I'd start by jumping into the deep end, i.e. I'd fully submerge without testing the water temperature first, in order to preserve the element of surprise. I've now backtracked on that, so I went down the steps at the shallow end (roughly waist deep) then immediately crouched down so that I was neck deep. I've learnt from experience that I will warm up if I start swimming, so it's best to get started as quickly as possible. If I stand still in cold water, I just get colder. It's a bit like the Saw movies, although obviously to a lesser extent: there's no real strength involved, so it just requires willpower to do something unpleasant because there will be a long term benefit.
I stuck to widths (in the shallow end) rather than lengths, and I did 8 widths altogether. In fairness, each width is 30m, which is longer than most indoor pools. That's 240m in total, which is equivalent to 12 lengths at the local Virgin Active gym (where I used to swim).
In all honesty, I have to say that this wasn't really fun; it was more of an achievement. However, I think that's mainly because I was adjusting to colder temperatures after my long gap, so I should enjoy it more if I swim more frequently. Mind you, I was amused to find a blog post from April (Freedom!) where other SLSC members were celebrating the fact that the water had warmed up to 10°C, so they were sunbathing!
During the summer, I found that I could pretty much drip-dry after I got out of the water, but at this time of year it takes longer (even with a towel). I also noticed some physiological effects from the cold. Trying to put this delicately, there was a certain amount of "shrinkage" - I effectively went through puberty again while I warmed up. I had a bar of chocolate (Bounty) and a can of Coke with me. I didn't really fancy a cold drink, so I just ate the Bounty, and I found that my jaw ached while I was chewing it. That's not toothache, it's simply from the movement involved. Once I got home, I had a hot Ribena, then sat down in front of a fire. (I had my chimney swept a fortnight ago.)
Today (Sat 30th) I went back again. According to lidosounds (audio blog by the same person who did the "Unusual Love Affair" photo blog last year), the water temperature went down to 9°C midweek. However, it was a bit warmer today: 10°C in the shallow end and 11°C in the deep end. (I don't quite understand the physics behind it, but apparently it's something to do with water pressure.) I started out with 4 widths, then did 2 lengths (91m each), so that's 302m altogether.
I've now started wearing a swimming cap again, and I was able to submerge my head for brief periods. Each "cycle" of front crawl involves 3 strokes: face down for 2, then breathing on the 3rd. I found that I can only do about 3 cycles of that before my face starts to freeze, so I mainly swam breaststroke. This keeps my head out of the water, although it's also slower, so I'm in the cold water for longer to swim the same distance.
After my widths, I stood up to take my goggles off, so that I could rinse them again to get rid of the fog. When I crouched down again, I actually found that the water felt warmer than the air, even before I resumed swimming, so that was nice. Also, the weather forecast predicted heavy rain but this didn't materialise. Instead, it was a clear blue sky, with the sunlight reflecting off the surface of the water, and I could feel the warmth of the sun as I swam around. That's something that I like about outdoor swimming, because you don't get the same effect indoors. (At the Virgin Active gym, the swimming pool is below ground level, so there are no windows.)
The pool has a sauna, so I decided to try the Scandinavian approach: swim, then sauna, then back into the cold water again. I went into the sauna, but I didn't feel particularly warm, and my forearms started itching for some reason. This meant that I was just sitting around while still covered in cold water (and wearing wet swimming shorts), without any movement to keep me warm, so I left the sauna, and I doubt that I'll try it again. I used the one at the VA gym a few times, but I tended to feel light-headed afterwards so I gave up on that too.
I dried off and got dressed, but I wasn't feeling in peak condition. I didn't take any chocolate with me, so I just had a can of Coke, and again this didn't seem particularly appealing. However, I only cycled about 500m before I had to stop. I wasn't going particularly quickly, but my pulse hit 148 (according to my heart rate monitor) and I felt dizzy. I drank the Coke, since at least it had sugar in it, and that gave me enough energy to cycle the rest of the way home (10km).
I realise that I'm not really "selling" the whole cold water experience when I describe these problems. However, they can all be solved with proper preparation. For instance, I now know that I need to take some food with me, and ideally a warm drink. Part of the reason I'm writing this is to warn other people what to expect, although I realise that most of my friends are far too sensible to start jumping into cold water!
Looking further ahead, the water will continue to get colder. In January, it was actually sub-zero! I'd like to keep going all winter, but I'm not committed to anything, so I always have the option of taking a break and waiting for the water to warm up again next year. I don't own a wetsuit, and it would be tricky to carry one on my bike. However, I may invest in some neoprene gloves. Earplugs might be useful too, since I've heard that cold water in the ears can affect balance.
Anyway, this all gives me a chance to be a bit adventurous, and it makes sense to take advantage of the lido while I live so close to it.