Tag Archives: freediving

Total internal reflection

In the “static apnea” discipline in freediving, many cool pictures of athletes are taken underwater in a way that plays with the reflection of the athlete in the still water surface. This can lead to pretty spooky pictures (like the one of Victor in the top left). We do have other experiences with water, where there are areas where we can look in (or out), but then others where we can’t: In the bottom left, you see Mats and his shadow, even the individual tiles very clearly in the water. But the further back you look, the more you notice that the picture was taken from outside the water, because you start seeing more reflections in the water surface. In the bottom right, taken from within the water, you see reflections of all the divers and the lane markings in the surface except right at Edvin’s elbow, where we look out of the water and see what’s happening above the pool. And then in the top right, we don’t see the water surface at all — the only reason we know we are looking at Alex from within the water is that there are bubble rings floating between us and him. So what is going on here?

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A simple way to visualize how hydrostatic pressure increases with depth

I did this demo for my freediving club Active Divers (and if you aren’t following us on Insta yet, that’s what I am taking all these pretty pictures for!): 1.5l PET bottle with holes punched in every 2cm, then filled with water. Looks cool and works pretty well (except the second hole from the bottom up, which I punched in a part of the bottle’s wall that wasn’t vertical, so the resulting jet doesn’t come out horizontally in the beginning and messes up the picture. Should have thought that through before…).

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Breathing practice: Where freediving and academic development collide

I recently wrote a lot about the emotions that we experience when really thinking about sustainability and the challenges that we face when we take it seriously (e.g. here), and of course experiencing negative emotions like feeling anxious or hopeless or angry is not only happening to our students, but also to us. I attended a seminar on “the sustainable teacher” yesterday and one suggestion that came out of that in order to help us work towards “inner sustainability”, was to include mindfulness meditation practices in our own and our students’ lives. And this reminded me of an article I recently read on breathing practice (which I find interesting from a completely different perspective, being a hobby freediver) in comparison to mindfulness meditation, where it turns out that breathing practice can be as effective or better than mindfulness meditation. So what if we included breathing practices in our teaching?

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A #KitchenOceanography escape game for freedivers!

For the Christmas party of my freediving club, Active Divers, I made a freediving-themed #KitchenOceanography “escape game” (of sorts). If you are interested to use it for your own purposes, please feel free to contact me for detailed instructions and material lists etc!

This is how it went:

We formed teams with three players in each, and each team came up with a team name, which they wrote on the same cards that they would later also write their “code” on.

Then, everybody got written instructions for three tasks (download here in English or Swedish). Each of the tasks includes an experiment and in the end, one of three answers to a question must be chosen, which ultimately make out a winning code. I had prepared two “hints” for each of the experiments that people could have requested had they gotten stuck, but that did not happen. Clearly, next time we have to up the challenge!

The experiments are not chosen randomly, they all connect to freediving experiences that the Active Divers group had together, and were embedded in a story:

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