Many (Most) of the rivers and lakes are swimmable in Switzerland, the standards for water are incredibly high, more dangerous is not knowing the currents.
Going down the Aare river from Thun/Uttigen to Bern is a hugely popular activity to do in summer, but every year a few people drown. Even so, I'd recommend it.
Swimming in Sydney Harbour is also possible. They did it for a leg of the triathalon in the olympics a couple of decades back. Wouldn't recommend though, there's a lot of bull sharks in there and they're kinda aggressive. Netted beaches and bays are the go.
I live in the eastern docklands of Amsterdam, and there's always lots of swimming here. Amsterdam has invested a lot in cleaning up its canals and other waterways and water quality has improved a lot over the past couple of decades. And there's no sharks.
I saw that, a bit further along from Kastrup sea bath, with the planes coming in to land at the airport.
I guess it's open water unlike the Seine, but it did surprise me, I felt like I was sat in quite an industrial area when a couple walked past in swimming costumes and towels.
In the 1990s, water quality in Amsterdam was pretty bad, but it's improved enormously since then. I live in the eastern docklands area and people swim a lot in the old harbour.
So is swimming in the Aare river in Bern, Limmat and Sihl rivers in Zürich, and the Arve and Rhône in Geneva. Floating down in tubes is a popular summer pastime.
Arve + Rhone in Geneva Jonction = pretty spectacle from Jonction bridge, where two distinct waters meet - crystal-clear Rhone which comes down from limestone (majority) part of Alps, has time settle any silt in Geneva lake, so it has easily 15m visibility, jut like most seas.
On the other side, Arve coming down from France is muddied right at the source by Mont blanc range, which is mostly granite. You can see the exact spot where specific stream comes into play, very gray, and it doesn't get much better afterwards.
Its enough to get big river like Rhone dirty all the way to Mediterranean sea. Also, after Jonction Rhone becomes pretty cold to just swim in even in warmest summer days. But yes many tkae it down during summer on inflatables, including us.
while the thames can be swam upriver of Putney Bridge, there are conditions as the Thames is a busy river. but there are other spots in London where one can do wild swimming.
Rotterdam here. People swim in the Maas all the time. Just be careful of the container ships and other water traffic.
There are lots of canals and rivers all across The Netherlands and people are swimming in them more and more. When I used to live in Utrecht the idea of swimming in the Oudegracht was disgusting. But I was visiting last month and saw people doing it. I still wouldn't swim in that canal.
Going down the Aare river from Thun/Uttigen to Bern is a hugely popular activity to do in summer, but every year a few people drown. Even so, I'd recommend it.
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