Barcelona’s open-water swimming event is the first round of the 8th Marnaton eDreams Cup.
The competition consists of three individual events of 6.5 km, 4 km and 2 km, setting off from the Fòrum, Mar Bella and Somorrostro beaches respectively and finishing at the Sant Sebastià beach.
A non-scoring 4x500m relay race will also be held at the Sant Sebastià beach, along with an event for children aged between 5 and 13.

https://agenda500.barcelona.cat/en/detall/marnaton_99400385266.html