As children growing up in eastern France near the Rhine, they learned to respect the river's power and beauty. Decades later, they met for the first time near the River Seine -- not far from where Claude Monet painted his iconic "Water Lilies."
The two hit it off, and it wasn't long before they turned their mutual passion for photography into a partnership.
They learned that they were both fascinated by the Rhine.
For thousands of years, the river has been a life-giving artery of commerce and transportation -- a natural border that both connects and separates vastly different cultures. After being threatened by devastating pollution, it's now experiencing a healthy resurgence.
Boissaye and Randé set about producing an unusual series of photographs that they took in the river -- literally. The project required them to go swimming with their camera equipment.
Aude Boissaye and Sebastien Randé
"I love swimming. I love water," Boissaye said.
"I don't like swimming. I don't like water," Randé joked.
In every photo, water covers the lower part of the frame. Above the water, the photos reveal Western Europe's different cultures. Below the water, they show a wide spectrum of colors and clarity -- from the Rhine's headwaters in Switzerland, north through Liechtenstein, Austria, Germany, France and the Netherlands.
"We chose the fish-eye perspective because it was interesting to be inside the river," Boissaye said. "To really see how the river looked."
The project speaks to different kinds of borders that separate people: cultural, political and social. Decades ago, the Rhine was very much a barrier separating France and Germany. But stronger European alliances in the late 20th century have led to more relaxed border crossings.
"It's very interesting that the border is virtually no more, because you can cross very easily now," Boissaye said.
The photos, Randé said, also speak as a reminder that people along the river "share the same space although we may not share the same culture."
Capturing images in the Rhine might be harder than you think.
"There are so many places where it's difficult -- or even forbidden to swim," Boissaye said. "Sometimes it was very difficult just to find a place to go into the water."
It took them six months to get permission to photograph the 70-year-old locks at Kembs in the French Alsace region. Dangerous underwater turbines from a nearby hydropower plant posed safety issues.
They came away with amazing photos of the locks' huge, 400-ton doors, which Randé said symbolize the river's industrialization. "When it first opened, it was the door to a new Rhine river," he said.
They used a standard digital camera inside a waterproof box made especially for diving. The lenses were mostly 50 mm and 24 mm.
Swimming with scuba gear underneath a towering door to get a photo, Randé said, was peculiar to say the least -- especially during November. As Boissaye put it: "When you're swimming, it's not easy."
Elsewhere, the pair had to walk for hours carrying scuba gear to reach remote locations near the river's headwaters in the Swiss mountains.
At one point along the river, they met a fisherman who wanted to talk with them about environmental issues. The river has largely bounced back from a devastating chemical spill in Switzerland that killed massive amounts of fish and plant life in 1986. A European Union report says environmental conditions in the river have improved greatly over the past several decades.
"The salmon are coming back, but not completely," Randé said.
Although they haven't taken a Rhine photo since 2012, they say the project isn't finished. They hope to get back to it as soon as possible. They also said they'd like to arrange a show and a book from the photographs.
The project contains three important components. "It's documentary and personal and artistic," Boissaye said. "And that's what we like."