First swimmers to complete the Stillwater 8

The first swimmers to complete the Stillwater 8 challenge, traversing eight iconic lakes across six continents, are brothers Joe and John Zemaitis (both USA), who crossed their eighth and final body of water (Lake Ontario, on the US-Canada border) in tandem on 23 July 2025. All of the swims have been ratified by the Marathon Swimmers Federation.

The Stillwater 8 challenge was first proposed by American endurance swimmer Michelle Macy in 2011. The octet comprises: Lake Ontario (USA/Canada), Lake Malawi (Malawi), Sea of Galilee (Israel), Lake Tahoe (USA), Loch Ness (UK), Lake Zurich (Switzerland), Lake Titicaca (Bolivia/Peru) and Lake Taupo (New Zealand); the set originally included Lake Windermere (UK) and Lake Baikal (Russia) but these were swapped for Malawi and Galilee in February 2020.

The siblings completed all their swims wearing only trunks, caps and goggles and their cumulative swim time was just over 81 hr 20 min. All of the swims were completed in tandem (i.e., started and finished at the same time), other than Zurich and Tahoe. The dates and times of the Zemaitis brothers' lake swims are as follows:

- Lake Zurich: 26 July 2015 (John swim time: 7 hr 40 min 23 sec / Joe swim time: 7 hr 55 min 58 sec)

- Loch Ness: 8 August 2018 (swim time: 11 hr 21 min)

- Sea of Galilee: 15 November 2019 (swim time: 7 hr 9 min)

- Lake Tahoe: Joe: 29 July 2020 (swim time: 11 hr 2 min 47 sec) / John: 28 August 2023 (swim time: 11 hr 21 min 9 sec)

- Lake Taupo: 20 February 2022 (swim time: 13 hr 45 min 10 sec)

- Lake Malawi: 7 October 2023 (swim time: 7 hr 49 min 42 sec)

- Lake Titicaca: 27 March 2024 (swim time: 5 hr 25 sec)

- Lake Ontario: 23 July 2025 (swim time: 17 hr 17 min 1 sec)