Paris Olympic champion Mertens set a new world record in the men's 400m freestyle that had been in the dust for 16 years

"Korean swimming icon" Kim Woo-min's opponent Lukas Mertens (GER) has set a new world record in the men's 400m freestyle that has stood for 16 years. On the 13th, Beijing time, Mertens won the championship in the men's 400-meter freestyle final of the 2025 Stockholm Open held in Stockholm, Sweden with a new world record of 3:39.96.

Lukas Mertens of Germany

Mertens swam 3:40 in the 400m freestyle for the first time, 0.11 seconds short of the previous world record (3:40.07) set by Paul Biedermann (GER) at the 2009 World Swimming Championships in Rome.

Mertens' previous personal best was 3:40.33 set at the German Championships last April. What's even more significant about Mertens' record that day was that he didn't use the full-body polyurethane swimsuit that Biederman wore when he set the world record.

At that time, there was even a "technical doping" of "technical doping" among competitors wearing such swimsuits, and a series of records were broken, so FINA began to restrict the material and shape of swimsuits in 2010.

This was followed by a new record dry spell that lasted for a while. Biederman's world record in the men's 200m freestyle set at the World Championships in Rome (1:42.00) has yet to be broken.

Mertens has swam the men's 400m, 800m and 1500m, including the 200m freestyle, and has been focusing on the 200m and 400m freestyle since last year, with rapid results. Especially in the 400m freestyle, he and his 2001-born peer Kim Woo-min recently competed for the title in international competitions.

At the men's 400m freestyle medal ceremony of the 2024 Paris Olympic Games, champion Mertens, runner-up Winnington, and third runner-up Kim Woo-min are on the podium

At the World Aquatics Championships in Doha, Qatar, last February, Kim won the gold medal in the 400m freestyle with a time of 3:42.71 against Eliza Winnington (Australia, 3:42.86). In third place was Mertens (3:42.96).

Five months later, at the Paris Olympics, that changed. Mertens finished the 400m freestyle final in 3:41.78 to win gold over Winnington (3:42.21). Third place went to Kim Woo-min with a time of 3:42.50.

At the 2022 World Championships in Budapest and the 2023 World Championships in Fukuoka, Mertens won the silver and bronze medals in the 400m freestyle, while Kim Woo-min finished 6th and 5th.