Swimming in cold open water: knowing when to stop / other safety tips
August 10, 2019 6:39 PM   Subscribe

I have the thrilling unexpected gift of several weeks next to a fjord that's easily swimmable when I'd assumed it wouldn't be. After 8 hours total in the fjord over 4 days, I'm feeling confident, but I want to keep being safe – especially after this heat wave fades. I'd love some advice about which sensations in the body you've found to mean it's time to stop (because the experience is so incredible I'm battling some strong "I don't wanna stop" instincts).

I'm on the Hardangerfjord in Norway, a bit east of Øystese (that's the nearest town for which I can find water temp measurements online, anyway).

Water temp here normally averages 60F in August; right now it's consistently around 65, which I've found totally pleasant for a couple hours at a time if I mostly keep moving. (Air-temp highs have been in the 70s, ranging up past 80; they're normally mid 60s.)

– I don't have, and can't reasonably get, any wetsuit/booties/etc.;
– I'm not pushing it in terms of distance; if I suddenly felt weak, I could easily make it in (and the entire shoreline is seaweed-covered rocks, very easily grippable even with cold hands);
– I have naturally low blood pressure and somewhat low body temp (not low enough to be on any meds for it);
– I have more body fat than the average strong swimmer;
– I'm swimming for pleasure not speed, keeping my head above water (doggy paddling or treading water), and waves vary here, but I'm more conservative if there are notable waves;
– I'm swimming only in daylight, but generally swimming alone (I'm at an artist residency where each person's time is their own, so I wouldn't ask someone else to watch me swim);
– Once I leave the water, I'm a few minutes' walk from a hot shower.
posted by kalapierson to Sports, Hobbies, & Recreation (8 answers total) 4 users marked this as a favorite

As someone who has swum for up to 4 hours at a time, in open water and pools, that sentence strikes me as optimistic. Everything from dehydration, to swallowing a bunch of water, to just "hitting the wall" can happen in minutes. And those temps may feel warm enough at first, but you need to be pretty active for it to not be an issue over a long period where you'll be losing heat. If you tired I'd be concerned about the temp, your ability to get back to shore, and your ability to react quickly to any emergent situations.
- Consider swimming with a small, bright buoy, which many open water swimmers use
- Is there any boating traffic? Consider a bright swim cap (at least!) or a swimmer's flag that's slightly raised from your body.
- Are there currents? Do you know where they are?
- What are the weather patterns?
- Leave a swim plan in plain view in your room so if you go missing people at least know where to look.

For me the first thing that goes is my acute awareness of where I am and where other things are in relation to me. In open water that's even tougher to gauge but it's still a good indicator that I'm tiring. It's like I've decided to take a break from caring so much and I get sloppy. Another is that my form fades and I'm in less control of how I'm swimming. I rarely get thirsty but have been dehydrated from swimming. If you're going to swim for hours, have a plan to re-hydrate.
posted by cocoagirl at 7:10 PM on August 10, 2019 [9 favorites]

65 is not that bad, but as summer ends it will get colder. In cold water, you run the risk of hypothermia. A big early symptom is feeling relaxed and sleepy while also feeling like you could swim forever. Decide when you have to turn back and do it.

Plan the swim and swim the plan. Tell someone when you will be back and what to do if you don’t show up. This is the same rule as hiking and going on dates, basically.
posted by blnkfrnk at 7:23 PM on August 10, 2019 [6 favorites]

Thank you, great questions! I won't threadsit, but I do see I was unclear, in that I'm definitely not at a level where I could continuously swim for anywhere near two hours straight. I just mean being continuously submerged in the water for two hours. The activity is small loops out from shore and back, with rests in between, either in standing-height water or on the submerged rock shelf by where my water bottle is. (Also: no boating traffic and low enough waves that for example I've swallowed no water in my first 8 hrs.)
posted by kalapierson at 7:34 PM on August 10, 2019

I'm a swimming dilettante, but I've had serious hypothermia twice. Once, mountaineering. Once, on a raft trip in Colorado in the middle of summer. The most useful advice I have is: hypothermia is fucking insidious. It comes along incrementally, and the first thing to suffer is your judgement.

I think this could go poorly very easily.

These guys seem a little more complacent.

IANASE (...swimming expert)
posted by j_curiouser at 7:34 PM on August 10, 2019 [7 favorites]

I can't speak to your current conditions, but I once did a water rescue in Maine for a guy who was a normally a good swimmer and well conditioned, who set out to swim to our boat, and lost all strength and began to drown, when the water was about 50 (he ended up OK, we got there in time, he took days to feel OK). Clearly, that was too cold without a wetsuit. This resource suggests that you are on the edge of dangerous now and should certainly not swim unprotected below 60.

posted by Miko at 8:53 PM on August 10, 2019

The first two things I would tell anyone are never swim alone, and don't swim long enough that you start to get "claw hands", which is one of your body's reactions to cold that makes your hands involuntarily contract.

And a third freebie-- you can't do much cold water swimming without also being forced into learning how to eat while swimming. It's a matter of heat loss forcing you into replacing those calories, and while you can just shove a sandwich under your swim cap (really, people do that), there are also special bland food pastes designed just for cold water swimming, along with float bags to hold them, etc. The blog I recommend below has several articles on how to get started with the whole process.

Probably the best resource for beginners on cold water swimming is a long running blog by a guy in Ireland. Of course, he picked the worst name in the world, as he himself will admit. I have lost countless hours reading his blog, which is called Loneswimmer.

It's got everything, literally. Just check out one of the dozens of how-to articles. It's the best resource I know-- all in one place, well written, and some attention paid to people who are just starting out.
posted by seasparrow at 9:19 PM on August 10, 2019 [7 favorites]

I've been outdoor swimming in Scotland for about 10 years, though never for nearly as long as you (in summer, I do about up to 30 minutes at a stretch max and always either within my depth or within a couple of metres' swim of it, tho tbh I don't swim a huge amount, just bob and chat and splash).

I think the problem is that you often can't rely on your physical sensations to know when it's time to get out. Often when you hit the point that you feel euphoric and like you could stay in forever, it's a sign that you've been in too long already.

From your talk of hot showers, I'm guessing you don't know a lot about blood flow and cold swimming, or the 'after drop', so:

When you immerse yourself in cold water, your body reacts by bringing a lot of your blood in towards your organs to keep them warm and functioning. This reduces the circulation to your extremities; the blood out there is cold, the blood near your core is warm. When you get out of the water, this effect releases and all the blood will start to circulate again, so all the cold water that was at your extremities floods towards your organs. You will, at this point, start to feel colder. This effect is known as the after-drop and it means that your core temperature drops in the period after you get out of the water, rather than rising. So you don't want to stay in until you're starting to get cold, because at that point, you've still got more getting cold to do. The worst thing you can do is have a hot shower when you get out of the water, because you'll accelerate this effect and probably faint, or feel very unwell.

* If you've been swimming for a regular period of time each day this week and feeling fine during and after, you've lucked out. Stick to that time, don't try and push it using the way you feel as a guide, because if you get out when you feel like it's a good idea, you've probably left it too late.
* Don't take a hot shower. As soon as you get out, have a warm drink, then dry your top half and get as many layers as you can onto your core quickly. Only when your core is dry and well-insulated, start to dry the rest of you.
* Put on more clothes than you normally would at this time of year - hat, gloves, thermals, are all common post-swim wear for outdoor swimmers, even in summer.

If you're there for long enough, you might want to order yourself a towfloat so someone can keep an eye on you from the shore. Nthing that it's not a great idea to be swimming on your own in unfamiliar water out of your depth.

I personally find that keeping my head dry makes it much easier to recover afterwards. If you want to put your head under but keep warm(er) and dry, you can wear two swim caps on top of each other.
posted by penguin pie at 7:27 AM on August 11, 2019 [12 favorites]

Thanks for a fantastic thread, especially to penguin pie for explaining the circulation sequence I didn't understand (and to seasparrow for recommending the Loneswimmer blog – as beautiful as it is useful)
posted by kalapierson at 12:47 PM on August 12, 2019 [2 favorites]

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