Salut,

The isodapane map: megretj.github.io/isodapane/national.html Last weekend, I went for a hike. Usually, with no Halbtax, I find the prices extremely high (e.g. a Zurich-Bern return ticket – a 2 hours travel in total – is above 100 chf) but this time I was positively surpised by the price of the public transport: a 4 hours trip to the mountains and back was below 60 chf. So I wondered, what’s the furthest I can get with a certain budget? This reminded me of a super cool isochrone map of Swiss public transport (isochrone.ch) that plots how far you can get within a certain time. However, as shown above, and against the popular saying, money and time aren’t quite homomophic. What we need is an isodapane map, that is equal-cost map. Turns out no one had done it yet. Falling for laziness, I asked Opus 5 to create is for me. And it did an alright job: megretj.github.io/isodapane/national.html ...

This is probably the question I get asked most: How do you plan your crossings? I’m very happy that people ask this because I think it’s a great exercise: try to come up with your own universal definition of something that feels intuitive. Most people will begin with: “Well maybe cross it across the width of the lake”. Of course that makes sense for a nice rectangular lake, but try to apply it to the Vierwaldstättersee… it doesn’t really much sense anymore, does it? So really: try to come up with your own definition and then apply it to different lakes, does it work well? If it’s missing to this post, send it to me and I’ll add it. ...

Along the way, I did other swims, either lakes not part of the list of 100 biggest lakes or just fun swims I got to do. Liberty Island swim Amazing swim organised by urbanswim ...

Glattalpsee 6th of September 2026, 38% Thunersee 5th of September 2026, 37% ...

Lungerersee 21st of April 2025, 1%. This marks the official start of the lake crossing challenge! Thanks to my mom and my younger brother Paul for accompanying me on this first crossing. I will hopefully come up with a structure over time how I write these blogposts, but here are couple facts about this crossing: Lungerersee It has three different orthographies: Lungerersee, Lungernsee and Lungerensee. That’s German for you. ...