Farthest swim with a monofin

The farthest swim with a monofin is 50 kilometres (31.13 miles) and was achieved by Merle Liivand (Estonia) in Biscayne Bay in Miami, Florida, USA, on 15 April 2023.

Liivand performed what is known as a "mermaid swim", which precludes the use of the arms and so relies solely on undulating the core and lower body and propulsion with the monofin/tail. She was in the water for 14 hours 15 minutes.

This is the fifth time that Liivand, now aged 32, has set this monofin distance record. She performed a 10-km (6.2-mi) mermaid swim off Redondo Beach, California, USA, in 2019 (time: 2 hr 54 min); a 20.6-km (12.8-mi) mermaid swim off South Point Park Pier in Miami in 2020 (time: 6 hr 8 min); a 30-km (18.6-mi) swim off Miami Beach, Florida, USA, on 17 April 2021 (time: 9 hr 19 min); and a 42.2-km (26.22-mi) "marathon mermaid swim" off Miami Beach, Florida, USA, on 7 May 2022 (time: 11 hr 54 min).

An Estonian National Team swimmer (specializing in breaststroke), Liivand is also a major advocate against marine pollution and uses her long-distance open-water swims as a means to draw attention to this growing environmental issue. Indeed, during this swim, she and her support team (in kayaks) collected about 20 lb (9 kg) of trash from the bay. Liivand told Reuters after the swim: "There are people who want to have this better, and that inspires me... we need to save Biscayne Bay. In 14 hours, my team picked up this. Every single person needs to do better because this came out from Biscayne Bay, where we all depend. We depend on it economically; we depend on it health-wise; we depend on the bay community-wise. If this is not shocking, then I don't know what to say."