Two silhouettes cut through the water a few hundred yards (metres) from a rainy, windswept beach bordering the flat grasslands near the small Inuit community of Wales, in the far west of Alaska.
Through the mist on the horizon, the islands of Little Diomede and Big Diomede -- the remote front line of the 40-year Cold War between the Soviet bloc and the United States -- emerge from the freezing seas like insurmountable walls.
On Little Diomede it is Saturday but across the Bering Strait it is already Sunday.
From the beach, the two swimmers could easily be mistaken for seals. Frenchmen Philippe Croizon and Arnaud Chassery are hoping that the killer whales that frequent these waters will not make the same mistake.
Croizon and Chassery are preparing to make the crossing between the two islands as the last stage of a challenge that has already seen them swim between Oceania and Asia, Africa and Asia then Europe to Africa since May.
The distance between Little Diomede and Big Diomede may only be 3.5 kilometres (2.2 miles) but these waters are no warmer than three or four degrees C (37.4-39.2 F) and often have strong counter-currents.
Then there is also the fact that Croizon, 44, is a quadruple amputee, having lost his arms and legs seven years ago after suffering a 20,000-volt electric shock as he tried to dismantle a television antenna from a roof.
Over the last three months, both men have swum from Papua New Guinea to Indonesia, across the Red Sea from Taba in Egypt to Aqaba in Jordan and from Tarifa in southern Spain to Tangiers in northern Morocco across the Strait of Gibraltar.
The aim of the challenge is to spread a message of "peace, solidarity and partnership", proving that disabled and non-disabled people can achieve the same goals.
The two men swim at the same sustained rhythm, Croizon instantly recognisable from a distance by the windmill movements of the front crawl stroke that he makes with the remainder of his upper arms.
When he gets out of the water, towelled dry by Chassery and the expedition doctor Arnaud de Courreges, Croizon is triumphant despite the signs of his efforts, cold and fatigue.
"I'm ready," he says breathlessly. "We have now been in the crossing conditions of cold and counter-currents. We're going to have to get across very quickly to avoid the eddies between the islands. But the Bering, I want to eat it up..."
Croizon's partner, Susana Catarino, 44, busies herself with the details. For every swim, she helps him into his wetsuit and fixes the prosthetic flippers to his thighs.
"I'm involved on all fronts: personal assistant, nurse, bag carrier, dresser, masseuse, psychologist, supporter," said Catarino, a accounts secretary who met Croizon seven years ago.
Together they arranged Croizon's first big challenge of crossing the Channel between France and England, which he achieved in 2010, bringing worldwide fame and hope to other amputees facing a similar predicament.
The 140-strong population of Wales are both confused and amused when Croizon rolls along the only mud road through the town in his wheelchair but he joins in happily with children's games.
Their laughs ring out like bells as they cling to his wheelchair, pushing and pulling it and turning it into a human train.
"These children see me as a strange prince come from the other side of the world," he said, his voice cracking with emotion. "They're my reward for having got this far."