Open water swimmer Ben Lecomte will spend the next six months in the ocean as he launches a daring bid to become the first man to swim across the Pacific.
The gruelling expedition will see Lecomte spend eight hours a day in the water for half a year as he tackles the 5,500-mile route from Japan to San Francisco.
Known as The Longest Swim, the challenge will see the 51-year-old cover an average distance of 30 miles per day - while facing such dangers as sharks, storms and jellyfish.
Lecomte's route will also take him straight through the Great Pacific Garbage Patch, the largest area of floating plastic and ocean debris in the world.
That is no coincidence, as Lecomte and his crew want to use The Longest Swim as a scientific study into pollution and oceanic research, as well as medical research into the effect of extreme exercise on the body.
He will be supported by a sailboat with a crew of six, as well as a team of doctors and other specialists on land remotely monitoring his physical condition.
Lecomte will swim during the day, and climb on board the sailboat to eat, rest and sleep. His GPS location will be marked each evening, so he can re-enter the water at exactly the same spot the next morning.
In a recent Reddit interview, Lecomte said he had a strict no-sugar diet during the swim.
"Most of my calories will come from a high fat diet and include a lot of freeze-dry full meals, rice, pasta and various soups, with olive oil added to increase the fat content," he said.
"I will try to consume around 8,000 calories per day. I will not be able to take in much food or drink while I am swimming, leaving me with only evenings and early mornings to try and eat as much as I can before jumping in the water again."
Lecomte will be wearing a magnetic bracelet to keep sharks away during the swim, but he also spoke of his respect for the dangers he could encounter.
"One of the tasks of the crew is to monitor my surroundings and alert me of any potential danger," he said.
"That said, I hope to encounter a lot of wildlife in the ocean, sharks included. It would be disheartening if we don't encounter many sharks or other animals.
"I respect them when I am in the water with them of course my heart races but they are a very important part of our ecosystem and we need to respect them. 100 million sharks die due to human activity so they're likely more scared of us."
Lecomte said he had been planning the expedition for four years. He has trained six days a week, usually three to five hours at a time, in the water as well as running and cycling.
"For me it's all about perspective," he added. "When I swim in the open water I always visualise myself swimming in a pool that moves along with me.
"I never really had any sort of fear swimming in the open water because I learned to swim in the ocean with my father at a very early age, so it's something I've grown to become very comfortable doing."
Lecomte set off from his starting point at Chōshi, Japan, this morning. He is aiming to reach the Californian coast shortly before Christmas.