In early June, Ben Lecomte will enter the waters off Choshi Marina Beach in Chiba Prefecture to begin a 10,000-km (5,400-nautical-mile) swim across the Pacific Ocean that seeks to shine a light on ocean pollution and plastic contamination, and put Lecomte into the history books as the first person to swim the Pacific.

“I’ve been working on it for the last seven years,” says Lecomte in advance of his departure. “So I feel like a tiger in a cage, I’m ready to go.”

Born in Paris, Lecomte, 50, is no stranger to the challenge of endurance swimming. In 1998, he became the first person to swim the Atlantic Ocean without a kickboard, a 5,980-km journey that took him 73 days.

His upcoming expedition is of a different magnitude, however. It is expected to take six to eight months and, all being well, Lecomte will finish his swim in San Francisco in December.

The expedition has been years in the making: It was originally planned for May 2013, rescheduled for December 2015, then April 2017 and finally, this June. The crew is now gathered in Japan, and everything points to a successful start.

“Finding the right support and scientific partners took a lot of time,” says Lecomte. “In 2013, we wanted to make it happen but we didn’t have all the elements aligned. The motivation was always there, I knew we were going to get it sooner or later. It is obviously happening a little later than sooner, but it’s happening.”

One of the biggest obstacles facing the swimmer was finding a suitable support vessel for the trip. “First we found an owner who was going to let us use his boat, but when we started talking about what kind of modifications were needed, it became an issue,” says Lecomte. “We found that the best way would be to acquire a boat. But finding the backers for that was a lengthy process and really challenging at times.”

The boat Lecomte acquired was Discoverer, a 20-meter, fully provisioned yacht that will accompany the swimmer on his journey and serve as home and shelter when he is not in the water. The boat will be piloted by a crew of nine (including Lecomte), who will be filming the journey for “The Swim” — a documentary series that will be broadcast on Seeker.com in partnership with the Discovery Channel — and conducting scientific experiments as Lecomte and Discoverer make their way across the Pacific.

“For six months, the boat will be completely autonom (autonomous), but we’d love to have a rendezvous along the way so we can pass on the data we’ve collected, pass on some video and also acquire some fresh food,” says Lecomte.

The expedition is taking place in collaboration with 27 different scientific institutions, including NASA and the Woods Hole Oceanographic Institution. Through the partnerships, Lecomte and the institutions hope to answer a range of questions, from the effect of phytoplankton on nutrient availability in the ocean to the impact of reduced gravity on the human body.

One of the main areas of research — and the one Lecomte is most passionate about — is plastic contamination. Over the course of the expedition, the team will collect more than 1,000 water samples in an effort to learn more about the concentration of microplastics across the Pacific. The route includes a swim through the plastic accumulation zone (aka the Great Pacific garbage patch), a 700,000-sq.-km gyre of plastic material that floats halfway between Hawaii and California.

“I have a deep connection with the environment, but unfortunately within my almost 40 years of swimming, I’ve seen big changes,” says Lecomte. “There is plastic everywhere, clean beaches I walked on when I was a child now have plastic. Do I sit back and not care about it? Or do I use my passion to shine a light on the issue?”

Using a wearable “RadBand” sampling device, Lecomte will also take measurements of cesium-134 and cesium-137 levels in the water to study the spread of radioactive material from the damaged Fukushima No. 1 nuclear power plant. With this, the crew will collect data on how far and how fast contaminants are moving, as well as their concentration across the ocean.

To aid his crossing, Lecomte has a team of routers on land, monitoring weather patterns and currents across the Pacific. And, to guide Lecomte, the Discoverer will tow a line behind it, allowing him to navigate across the landmarkless ocean.

The route from Japan to the U.S. follows the Kuroshio and North Pacific currents that flow west to east, giving Lecomte some assistance. Even so, to complete his journey as planned, Lecomte will spend eight hours a day in the water and burn an estimated 8,000 calories a day. But the greatest challenge isn’t the physical, but the mental, he says.

“My heart rate won’t be that high, normally between 110 and 120 beats per minute. So it’s really mind over matter, you have to rely on the mind to keep you going,” says Lecomte. “I start my day with a schedule to allow me to focus on the right things, to dissociate my mind from my body. My mind will be doing exercises throughout the swim, while my body will be running on autopilot.”

At the end of each day, Lecomte will log his GPS position and will then eat, sleep and recover on the boat, before resuming his journey the next day from the point he left the water.

With six months at sea, there is obviously some danger to both swimmer and vessel. But Lecomte embraces this with a cool eye for risk. “Sometimes you have a storm with nice waves that come from behind you, and I love those because then you get some big surf,” he says, laughing. “But if there are waves in every direction, and the risk is too high, I won’t be swimming that day.”

Ultimately the expedition is a personal one: Lecomte will seek, if not to conquer, then to coexist with the awesome power of the Pacific. But through his efforts, he hopes that the expedition will become much bigger than himself.

“I want to make people aware of the environmental degradation of the ocean; as a first step I hope people can take a step away from using single-use plastics,” says Lecomte. “It’s not a problem we don’t know how to solve, it just requires awareness and for us to change our behavior. That’s why I’m doing this swim, that’s what keeps me motivated.”

Videos from Lecomte’s expedition “The Swim” will be broadcast daily on Seeker.com , or follow along on Lecomte’s website thelongestswim.com