What’s that all about?

Somehow, I told too many people I was going to cross the 100 largest lakes in Switzerland. So here we are, I will attempt it and share some of my experiences right on this website. It’s a stupid to expose the project before actually having started it, but hopefully I will push me to actually do it. Anyway, talking about this project sparked many interesting questions that I’ll attempt to answer throughout this adventure.

Choosing the lakes

Let’s start with the simple stuff; which lakes are considered ? Well actually it’s not that simple, first what is a lake? Well,there is no universal definition. When is it a pond? When is it a river? When is it a sea? Ok, maybe you’re thinking I’m being pedantic, and I probably am, but definitions and rules matter, otherwise people will argue. So I will try to be as transparent as Oeschinensees water and explain my methods and rules.

Using the 1:500'000 map from swisstopo, I arrived to the following “short"list:

Further pedantry

A couple remarks though. First, the areas aren’t exact, they won’t match what you would find on wikipedia. This is a consequence of a well known phenomenon called the coastline paradox. The larger your unit of distance, the rougher your shorelines will be, and therefore your measures will differ. For shorelines, this means that there is no well-defined length. The area does have a well defined limit but the fact that the map I’m currently using is quite rough, it will “cut corners”. But this should not impact too much the ordering of the lakes (perhaps the smaller ones are a bit shuffled around, but sometimes in life you have to cut corners to get things done).

The second point is that lakes move more than we initially think. First you have the reservoirs from hydroelectric plans, which size fluctuate in size to the rythm of people querying chatgpt to plan their next trip to the maldives. Furthermore, lakes (glacier lakes in particular) also fluctuate naturally and skrink drastically at the peak of summer time. I didn’t really think much further on this point and trusted the map. But it might mean that I will cross a lake by jogging it.

Also, many lakes are in two or three countries. I just want to note that those also count, otherwise I would get rid of three of ther four largest ones. But to keep the “swiss” aspect to the challenge I will restrict myself to start or finish in Switzerland.

Finally I took the liberty to exclude two “lakes” which, given their surface area, would have been in the 100 largest in switzerland. The Häftli and the Alter Rhein. I don’t think many people ever considered them as lakes, as they are both old river beds of the Aare and the Rhine, respectively. And they would have been a bit boring from a crossing point of view.

The rules

1. Swimming with a buoy is mandatory.
2. Swimsuit is allowed but no other swimming helping devices are (no fins, snorkel, underwater jets)
3. I must stand on firm ground on both sides.
4. I holing on to anything during the swim will cancel
5. I may divert from the original trajectory^{1 2} for different reasons but the swimming distance must be at least as long as this one.
6. Lakes may be crossed in any order.

I’m sure I forgot some edge-case, so I might add other rules later.

Oh of course! I also will try to never take a car to get to any of those lakes. The plan is to only use the bike. And I will indeed try to hold this with the caveat that I can take a train on a segment where I already cycled. I’ll talk about it another time.

When does it start? And how long will it take?

Well hopefully as soon and as short as possible. But realistically, I will start the first swims in the coming month. And I don’t have a deadline but I will try to do it within the next two years. However, feel free to remind me that I’m not making progress. I will do updates on this website and post my swims on strava.