Here is the video without the very slow site: https://www.youtube.com/watch?v=v3O9vNi-dkA

Here is what happens, when he falls through ice:

https://www.youtube.com/watch?v=Px5uQuRT3EE

Wasn't he looking? That thin patch was really obvious.

If you want to be safe, you need to intentionally fall in a lot in order to practice getting out.

Generally true of all dangerous activities. This is the purpose of “play” you practice dangerous things in relatively safe, intentional “silly” space, so when you have an actual leopard trying to eat you, you’re not trying newbie stuff for the first time.

You make a good point, but I had a laugh picturing him going "alright, managed to get out of the ice safely. I am 100% ready for leopard attacks."

Maybe in retrospect. But could be also "safe" ice can look like that?

Maybe, although whenever I've seen ice like that it was because there was a large air bubble trapped below and the ice was thin.

Interesting. It looks like he just uses those picks to keep clawing his way through thinner ice until he reaches thick enough ice that doesn't break. Seems like that could be dangerous if the thin ice goes on for long enough that you freeze before you reach a thicker region.

You're supposed to turn around and go back on to ice that you know is safe.

Also when you are out of the water, roll like a log to thicker ice, instead of standing up. This is to reduce chances that the adjacent ice breaks under the pressure.

PSA: Never go to thin ice, or ice of unknown thickness, without company, ice picks or claws [1], and a plan for how to get to warmth after a water excursion. Remember that ice strength and thickness depend on multiple factors and may vary rapidly from one spot to another. Make sure you know how to get out of water should you fall in, and how to safely assist a companion if they do.

[1] http://lakeice.squarespace.com/ice-claws/

A special note should be dedicated to river ice. The running water can pull one under the ice, which is very dangerous.

And ice is thinner where there is running water.

It's a bit weird seeing this now, since we're currently experiencing a heat wave here in Sweden that's been going on for about two months now. It's around 30 degrees C and very little rain, so farmers have to send their cattle to early slaughter since there's no food for them. The water supplies are really low, and trees and grass have turned yellow.

Yeah, inside the forests it is dry and one can really see how some plants are struggling. It is a dry heat, barely any moisture at all. Today it was near +30 C. The ground with pine/spruce needles and moss smells fantastic though, something resembling warm cinnamon.

When one encounters a field or an opening with grass, it is more likely than not burnt, yellowish ferns are a norm rather than an exception at this time of the year, and ditches which used to have a stream of water are barren.

If the upcoming winter is dry without much snow, the ground water levels won't be replenished and, with the lack of rain, next year will be worse.

The high heat creates local thunders with apparently do not carry much rainfall. Lightning strikes seem to have started at least a few of this years forest fires.

Searching youtube for ice skating on black ice led me to apetor a while ago - one of the few channels I subscribe to. There's something strangely soothing about how goofy this guy is.

https://www.youtube.com/watch?v=S1Q2jwEX11U&list=PL73A6AD7F0...

What makes it safe is the assumption that when you fall, it's not a big deal when you are prepared.

If you have been swimming in ice-water, you already know that you survive several minutes without a problem. Ice claws hanging from a neck strap make it easy to crawl into safety. You have dry clothes in watertight container in you backpack if you are far away from warmth, of course.

I was curious about ice claws and found this informative: http://lakeice.squarespace.com/ice-claws/

Edit: and if I'd read a few comments down I'd have found this without Google.

I was expecting something fancy compared to the barn spikes I carry on the ice with a name like ice claws, but nope they are basically the same damn thing.

Better handles for manipulating with cold numb hands seems like an important feature.

I'm fascinated by the description “laser-like” for this sound. Does this touch on a broader synaesthetic phenomenon or it based on the historical sci-fi presentation of laser/phaser guns? I suspect the latter.

I think the first use of that sound was in War Of The Worlds in 1953, they didn't even had lasers at the time :) I couldn't find any explanation, how they arrived at the sound (it's supposedly just electric guitar + reverberation).

https://youtu.be/G5H4yK_tiGI?t=116

It's very popular in Sweden really, it has had the right kind of lakes and climate to often produce the conditions for it.

There's nothing "wild" about this, not more than taking a run in an actual forest.

There's also "wild swimming" [1], swimming in natural waters. From a Nordic perspective there's little "wild" to it but apparently it can be an exotic experience in other countries. I wouldn't be surprised if "wild running" was a thing somewhere, after all in many places like England finding an actual forest to run in can be highly nontrivial.

[1] http://www.wildswimming.co.uk/

I don't understand, is there a way to assume you would swim in something that's not natural?

For me, in Brazil, surrounded by waterfalls and beaches it's not only common but also necessary for you to relax sometimes.

I think the distinction is between places in the wilderness (peaceful) and tourist beaches (not-so-peaceful).

I think in the UK both waterfalls and beaches are in short supply.

There’s quite a few beaches in the UK, https://www.thebeachguide.co.uk/south-east-england/.

Where I live I know many people who do both of these things (including myself). But we're surrounded by water and forest! It makes good sense to get out into it. I have a 7mm wetsuit so I can swim year round.

I’m curious, do people create elaborate illustrations on the ice or make any other use of it?

What’s not wild about running through an actual forest?

The forest could have markers indicating the track, could have bridges built to cross small streams, or even parts with paved (gravel or worse) paths.

Indeed, if the forest had not been tamed, not had some part of it claimed from the wild, it would be neigh-impossible to run in it.

That depends a bit on the kind of forest (some forests have way less ground cover than others) and on how you define “forest” (e.g. if a river that floods regularly flows through a forest, do you consider its shores to be in the forest?) and “running” (e.g. are the Barkley marathons (https://en.wikipedia.org/wiki/Barkley_Marathons) a running race?)

Good points, so the ice skating is a bit more wild with this perspective, if it's an "untamed" lake. (There certainly exists tamed lakes).

Mesmerizing video! A mathematician exercising predictive control over thin ice brings to mind Kislowski's wonderful Dekalog 1 (https://en.wikipedia.org/wiki/Dekalog:_One), which is my favorite among the set of ten.

There seems to be a rule of thumb for black ice strength: kilograms = centimeters squared times 5. Seems to jibe with recommendations for a 80 kg walker (4 cm), 2000 kg car (20 cm) or big 48 ton truck (1 meter).

With less and less snow hitting the Sierra early in the winter season the lakes stay snow free longer with good ice. I've seen people out skating, particularly on the drier and colder Eastern Side. I think I'll try and go skating up near Carson pass this winter, maybe hike out to Winnemucca lake if I want to carry some skates in. Should be a nice change from hiking before snowshoe/ski season starts.

I did some of this at Hellasgården, Stockholm in January this year. The rising sun makes for a spooky video: https://youtu.be/WdmCIC2Hoks

After learning more about this, I would only go with other people now.

Bonus video: https://youtu.be/eGdvQVoQOUQ

The current title here is "Nordic Ice Skating on Thin, Black Ice in Sweden Is an Art and a Science". The NatGeo title doesn't currently have "Nordic Ice" at the beginning, and it doesn't seem to parse (at least, not without a colon: "Nordic Ice:" or so). Is it really supposed to be there?

If there is no ice on the lake, how about water motocross. With a dirt bike, not an aquabike/waterjet. https://yle.fi/uutiset/3-10298809 (finnish text).

I love that "Trygg" literally means "safe" in Swedish. :)

Epic aptonym.

I live in Zürich and just met a gentleman who goes to Sweden and Russia every winter to skate on frozen lakes. I had never heard of this, but was fascinated by his videos, pictures, and stories.

45mm isn't that thin, is it? As a kid, I always learned that ice had to be at least 5 cm thick. This is only half a cm less.

It leaves you with perilously little error margin though. You have to be very aware of spots of potentially weaker ice, like places with water currents. With such a small surface area, skates also create a much greater pressure against the ice than shoes, though I'm not sure how exactly that affects the dynamics in practice.

We wore skates too, obviously. Weak spots were generally recognisable by there being no ice at all, and we kept a safe distance from such spots.

A quick search turned up these guidelines for ice: http://www.natuurijswijzer.nl/ijsontwikkeling/ijsdikte/

Is says:

  0-4 cm: unsafe
  4-8 cm: strong enough for a single skater
  8-12 cm: suitable for larger numbers
  12-15 cm: time for the Elfstedentocht (a 200km skate marathon; we haven't had one in 20 years)

Careful, the website hijacks the back button (at least on my mobile device. iPhone 7Plus.) One of the most infuriating design anti-patterns.