The middle-aged couple sauntered hand-in-hand through the centre of Zurich on a warm, late-August evening. The twilight was illuminated by the 11th Century Fraumunster church while cafe terraces hummed with people enjoying plates of air-dried beef and icy cocktails.
As the couple passed me they left a trail of wet footprints in their wake – despite being one of the busiest streets in Switzerland’s largest city, the only thing the man was wearing was a pair of damp Speedos while the woman sported a black swimming costume.
But no one – except me – batted an eyelid. Even at 9pm, the temperature by the banks of the River Limmat hovered around 30C (86F), and for locals a dip in the river or lake in the middle of town is nothing unusual at all.
Splash out: The jetties of the Utoquai badi, which is divided into women/men/mixed sections
The ace up Zurich’s sleeve is its badis, or lake-side open-air swimming pools, some of which are more like nightclubs, featuring bars and DJs. Their humble 19th Century origins, though, were to give locals a place to scrub up when the washing facilities at home mainly consisted of a rag and bucket.
And autumn is a perfect time to explore them, with the summer tourists gone.
The one in which I like to start the day is Seebad Enge (seebadenge.ch; entry £6.60) because it catches the morning sun. I have a refreshing dip in the lake with the Alps in the background followed by a breakfast bowl of fruit and yogurt and a freshly brewed coffee.
Then you can swim back to one of the floating pontoons for some sunbathing or, like many others, bag a table near the entrance and power up your laptop to use the badi as an al fresco office. Enge also has a sauna for chillier days and activities that range from massage and yoga to bootcamp workouts and stand-up paddleboarding.
In the evenings, Frauenbad at Stadthausquai turns into a bar that is open to all – as long as everyone takes their shoes off
An equally chic alternative is Seebad Utoquai (entry £6.60), a bathing club built on a series of wooden jetties over the lake, that first opened its doors in 1890.
It’s divided into women/men/mixed sections and it’s busy all day, from 7am when suited bankers strip off for a pre-office dip. Details can be found at stadt-zuerich.ch.
Later on, smart ladies and gentlemen who lunch come to top up their vitamin D, spreading out thick towels so as not to get splinters from the floor planks while catching up with the papers.
The terrace bar at La Reserve Eden au Lac Hotel is a lovely spot for sundowns, says The Mail on Sunday’s Will Hide
On a warm day I’d save Utoquai for the afternoon, so you can pop over the road afterwards to the Philippe Starck-redesigned La Reserve Eden au Lac Hotel (lareserve-zurich.com) for sundowners.
Take the lift up to the top floor and head right to the terrace bar, where a Summer Fizz of vodka, lemon, basil and watermelon will set you back £17, or turn left to the terrace of La Muna, a Peruvian-Japanese fusion restaurant with dishes such as creamy spicy tuna tartare and dragon roll sushi (mains cost about £25).
A more egalitarian experience is to be found in the River Limmat itself where, at the Upper and Lower sections, youngsters congregate to plop into the water from the path, or, if they’re braver, to jump off bridges and float down on the swift currents.
Head for heights: Enjoy panoramic views over Zurich from the top of the Uetliberg mountain
Will Hide was a guest of the Swiss Tourist Board (myswitzerland.com) and 25 Hours Hotel Langstrasse (25hours-hotels.com) where room-only doubles start from £165. Some badis close from October: details at zuerich.com. Swissair (swiss.com) flies to Zurich from Heathrow (from £84 return) and Manchester from (from £128 return).
At the end you might bounce rather forcefully into the sluice gates, which can be a bit painful on the shins, but it’s just a quick walk back down to the terrace of the cool Panama Bar (panamabar.ch) to watch the world go by over a plate of calamari (£10) or a juicy burger and chips (£17).
If you want to experience all this al fresco fun without taking the plunge, wait till evening. One of my favourite things to do on a balmy autumn evening is to slip off my shoes at the usually women-only Frauenbad at Stadthausquai, which admits men after 8pm when it transforms into the dreamy Barfuss Bar (barfussbar.ch).
Barfuss – barefoot in German – is the rule. Leave shoes at the entrance and sidle up to the bar for an Aperol spritz and then sit with your feet dangling in the lake as you take in the gorgeous views over to the old town and, depending on the evening, listen to a local DJ. A 15-minute walk away you can do much the same at the equally cool Rimini Bar (rimini-ch), which until 6.30pm is the men-only Mannerbad Schanzengraben badi.
If you’re starting to think you have to have webbed feet to enjoy Zurich, fear not. Head to platform 22 of the main railway station and a little red train will take you on a 20-minute ride almost to the top of the city’s own mountain, the 2,800ft Uetliberg (one-way tickets, £3.70). Once up there you can enjoy panoramic views over the city.
Then you can either hop on the train to come back down again, or walk through the woods for two hours to Felsenegg and take the cable car. You probably won’t see anyone hiking in swimming costumes but, in Zurich, never say never.