Olympic champion Adam Peaty says the International Swimming League is revolutionising the sport after 25 years of "doing it wrong".
The last leg of the fast-paced, franchise-based league started on Saturday (23 November) and finishes on Sunday (24 November), with four of the eight teams from Europe and the United States competing at a sold-out London Aquatics Centre to secure a place in the finals in Las Vegas in December.
Fina, the sport's governing body, initially indicated it could ban athletes who took part in the ISL, but backtracked on the threat in January this year following a furious reaction from Peaty and many of his fellow elite swimmers.
Peaty, who swims for London Roar, told BBC Sport the new privately-backed format was "exciting and dynamic" and just what swimming needed following its launch last month.
Read more from Adam Peaty here.
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The International Swimming League is a new team-based competition format for 2019 with fast-paced race sessions between eight teams composed of both men and women.
The league consists of seven swimming meets which take place in seven cities around the world. The regular season started in October has seen action in Indianapolis, Lewisville and Maryland in the United States, Budapest in Hungary and Naples in Italy ahead of the final meet of the regular season in London this weekend.
Each team competes three times, twice against in regular competition against fellow teams followed by a 'derby match' against their regional counterparts (European teams & United States teams), which includes this weekend's event between the European teams.
Teams competing this weekend:
London Roar (Great Britain) captained by Great Britain's Adam Peaty
Aqua Centurions (Italy) captained by Italy's Federica Pellegrini
Iron (Hungary) captained by Hungary's Katinka Hosszu
Energy Standard (Turkey) captained by South Africa's Chad le Clos
Follow live coverage of the London leg of the International Swimming League across BBC Red Button, Connected TVs, BBC Sport website and app.
You can also watch live on BBC iPlayer and on catch-up for 30 days here.
Sunday 24 November
Day One: 17:00-19:00 - BBC Red Button, Connected TVs, BBC Sport website and app plus BBC iPlayer
One of the nation's most popular activities, swimming is for anyone and everyone. From chilling out on the inflatables to doing several laps in the deep end, it's hard not to love a dip in the pool.
Watch endurance athlete & blogger Sophie Radcliffe explain how swimming in an open-water environment is an "exhilarating" experience.