This is the fastest 10k you'll find: the Hurly Burly, an autumn 10k on the Mawddach in North Wales - with a run and a run-swim option.

Set in North Wales on the edge of Snowdonia, this swim is the most beautiful we have ever found. It starts on the sandy beach of Barmouth, and takes swimmers underneath Barmouth Bridge, a mile and an iconic half wide railway bridge. The first part of the swim is up the wide and sandy estuary (hopefully with the wind behind us) with mountains on either side, and then its through the narrows and into a more sheltered part of the estuary.

The whole swim takes place on a fast, incoming Spring tide that works like a bore to assist your swim. Past the narrows the water speeds up further, and the landscape becomes pastoral, the banks closer to you. The swim ends at Penmaenpool, where we will get changed, gather for hot food and to warm up on fire pits, and celebrate.