Swimming in the Limmat

I did not plan to become someone who swims to work. It happened by accident, on a hot Tuesday in July, when a Zurich friend told me the fastest way back to the old town from Oberer Letten was not the tram but the river itself. She was not joking.

Where Zurich actually swims

Zurich sits on a lake, but the lake is not where the city does its daily swimming — the Zürichsee boat trips are for a slower afternoon. The real summer habit runs along the Limmat, the river that drains the lake through the middle of the city. Two public river baths, Oberer Letten and Unterer Letten, sit about 700 metres apart on the western edge of downtown, and between June and August they are as central to Zurich life as any museum on a things-to-do list.

The Badi system, briefly

A Badi is simply a public bathing facility — part swimming pool, part social club, part changing room. Zurich has dozens scattered around the lake and the river, but the two Letten Badis are the only ones built directly onto the Limmat’s current rather than a still basin. They open for the season around early May and close by mid-September, weather depending, and entry is free. There is a small kiosk for beer, ice cream and Bratwurst, wooden decking to lie on, and lifeguards on duty through the bathing months. None of it is glamorous. All of it works.

Oberer Letten: the one everyone means

When a local says “let’s go to the Badi,” they usually mean Oberer Letten. It has a proper changing building, showers, lockers you can rent with a deposit coin, and a long grassy bank that fills up fast on any day over 25°C. The entry point into the current is a ladder at the upstream end; you climb down, brace, and the river takes you from there. If you would rather not deal with moving water at all, there is also a calmer, partly enclosed pool fed from the river, which is where families with small kids tend to stay.

a local-guided bike ride along the riverside path is a decent way to scout the whole stretch before you commit to getting in the water yourself, since you can see exactly where the exit ladders and the rougher patches of current sit.

The current, the temperature, the technique

This is the part nobody explains clearly before you go. The Limmat’s current between the two Letten baths moves at a fairly brisk, steady pace — you are not swimming so much as steering. Point yourself diagonally toward the far bank if you want to land somewhere specific, keep your feet up and pointed downstream in case you hit anything shallow, and expect the trip from Oberer Letten to Unterer Letten to take roughly ten to fifteen minutes, depending on the water level that week.

Temperature swings with the season and with how much Alpine snowmelt is still feeding the lake upstream:

Period	Typical water temperature	What it feels like
Early June	15–17°C	Sharp on entry, fine once moving
Late July–August	19–22°C	Comfortable, most crowded
Mid-September	16–18°C	Bracing, thinner crowds

Compare that with the numbers in the month-by-month weather guide before you plan a swim-focused visit — a warm forecast in the city does not always mean warm water, since the Limmat is still lake outflow, not a heated pool.

What the locals actually do (and don’t)

The unwritten rules are mostly about the dry bag. Zurich swimmers seal their clothes, phone and shoes into a waterproof bag shaped like a fish, called a Wickelfisch or just a Fischli, and let it trail behind them on a cord while they float. You do not need one to swim here, but if you show up without one and try to carry a plastic bag one-handed above the water, expect a few amused looks. Rental or purchase points sit near both Letten baths in summer.

What locals do not do: swim after a storm. When Zurich gets a heavy downpour, stormwater can overflow into the sewer system and briefly raise bacteria levels in the river. The Badis post warnings and the lifeguards will wave you off if it is not safe that day — it is one of the few rules that is genuinely followed rather than politely ignored.

Dogs are kept out of the Letten enclosures themselves, though the riverside paths around them are full of owners letting their dogs paddle from the bank. Nudity is not really part of the Letten scene, in contrast to a handful of quieter stretches further from the centre.

When it doesn’t work

Skip it in early May if you are not used to cold water — 15°C feels genuinely sharp, not refreshing. Skip it on the hottest weekend afternoons if crowds bother you; Oberer Letten’s decking gets shoulder to shoulder by early afternoon in a heatwave, and arriving before 10am or after 6pm is the only real workaround. And skip it entirely after a storm warning, no matter how tempting the sun looks an hour later — the water clarity itself usually tells you before any sign does.

If the Limmat itself is not enough water for one trip, the Rhine at Schaffhausen has its own, much larger current-swimming culture below the falls, and it is an easy day out by train. Closer to home, the quieter reaches of the lake described in the quiet side of Lake Zurich are worth it if you want stillness rather than current.

For a longer, slower way to see the river itself, both a self-guided rafting run down the Limmat toward Dietikon and a private guided float that walks you through exactly how locals do it stretch the same idea well beyond the ten minutes between the two Letten baths. If you would rather combine it with a short trip out of town, a private day out to Baden with a Limmat riverside walk follows the same river further upstream, past its own set of thermal baths.

None of this needs to be booked in advance or planned around. Bring a swimsuit, a towel, and a few francs for the kiosk, walk down to Zurich’s old town afterwards while your hair dries, and you will have done the one thing in this city that costs nothing and every local does anyway. Check the getting around Zurich guide if you are coming from further out — both Letten baths are a short tram ride from the main station, not a taxi trip.

For families weighing this against other options, the family day trips from Zurich guide and the wellness and spa category cover the calmer, heated alternatives for cooler months, and the best time to visit tool is worth a look if the whole trip is being planned around warm water rather than around sights.