Swim London 10km – Trial Swim

Olympic swimmer Toby Robinson is creating an exciting new swimming challenge in London

After Toby Robinson swam in the 10km Marathon Swim in the Paris Olympics, he asked himself a simple question: why can’t we do this in London?

The Thames winds through the heart of London. It’s world-famous and iconic. One hundred years ago, bathers crowded the shore at low tide around London Bridge. Our Houses of Parliament offer stunning views over its swirling waters. Some would say England is the birthplace of marathon swimming, after Captain Webb swam across the Channel in 1875. Surely the Thames could be an amazing venue for a swimming event.

On the other hand, it’s wide, tidal and murky. It floods and ebbs twice a day, rising and falling by several metres. The powerful tidal currents run one way and then the other, creating confusing eddies around bridge piers and jetties. It’s busy with rowers and commercial traffic. The Port of London Authority considers it so dangerous that it bans swimming downstream of Putney Bridge. Historically, it was heavily polluted, and the reputation lingers.

So which view of the Thames wins? Is Toby’s vision delightful or delusional?

To find out, I joined Toby for a trial swim of his proposed route down the river, in the stretch above Putney Bridge where swimming is allowed.

Going with the flow

Starting from the Liquidity Statue in Brentford (opposite Kew Gardens), we entered the water via a slipway about 20 minutes after high tide. The current had already turned, and the water was accelerating downstream. I almost lost the pack right there as I’d been taking pictures and was scrabbling to pack my phone into my tow float. In the 30 seconds it took me to do that, the others were already 50m downstream. I sprinted to catch up.

Under the watchful eyes of the Port of London Authority and a full safety team, Toby, I, and six other swimmers crossed the river to the right bank. This first section has a wild, rural feel, with trees on both sides crowding over the water.

Within a few minutes, the current whisked us under Kew Bridge. It was here that I appreciated for the first time just how fast we were moving. The bridge was gone in an instant. The kayakers guided us closer to the middle of the river to avoid a pier and then nudged us back towardss the bank, out of the fairway. We soon passed Oliver’s Island and Kew Railway Bridge, and sped on towards Chiswick Bridge. The familiar landmarks provided both reassurance and a sense of speed. You would have been hard-pressed to match our pace on foot.

At Barnes Bridge we paused to regroup. But, even without swimming, we kept moving at speed. From here, the river sweeps around a wide bend to Hammersmith Bridge, and we suddenly felt the effect of the wind as it became choppy for a while, but we already knew the end was close. At the bridge, I rolled onto my back to admire the structure. I could relax properly now, knowing we were nearly done.

We then passed the Wetland Centre – another stretch that felt rural, on one bank at least. On the left, we had a brilliant view onto Craven Cottage, the home of Fulham Football Club. Finally, Putney Bridge came into view. We headed to the bank, and it was all over.

We had covered 10km in 90 minutes, including pauses to admire the views and chat. That’s an average pace of around 54 seconds per 100m. In contrast, Toby took just under 2 hours to cover the same distance while racing in Paris. It made us feel bionic and everyone was grinning, even though we knew the river had done most of the work.

Sewage intercepted

But what about those pollution worries? The Thames is a natural environment through a major city, so it will never be pristine, but the quality has improved significantly in recent years according to monitoring by both Thames Water and independent citizen scientists. In 2025, the Tidal Thames Tunnel came into operation. It’s intended to reduce spills of untreated sewage into the Thames by 95%. It’s not perfect, and campaigners have recorded spikes in bacteria after heavy storms, but pre-swim testing showed E.coli and intestinal enterococci levels under the threshold for excellent bathing water status.

And the currents?

Make no mistake, currents can be dangerous. They can sweep the unwary away or pin you against obstacles.

But you can swim in them safely if you’re mindful of the risks.

We had full safety support for the trial swim with kayakers to steer us away from any obstacles. This meant we could simply enjoy the ride. I was swimming perhaps 50% or more faster than I could in still water, and it was exhilarating watching the scenery flying by.

Toby thinks swimming with the current will be a key attraction of this swim, and I agree. He even speculates that the right swimmer on the right tide could complete the swim in under an hour.

Watch this space

I loved my swim, and I think it has all the elements for a brilliant challenge: an attractive and famous location with iconic landmarks combined with the thrill of being swept through London by the outgoing tide. It’s a 10km swim that feels more like 5 or 6. But if that still feels too far, there will be a 5km option too. If the trial swim is anything to go by, this will be an amazing event.

Practicalities

It’s logistically easy too. The start is a 15-minute walk from Brentford Station and the finish a similar distance to Putney Station. There are plenty of buses or rental bike options as well. Spectators can watch from the towpath, but they will need to run or cycle to keep up.

The event is planned for 6 September, and tickets will be available shortly from https://swim.london/ – register now for priority access.