“I speak to you from the cockpit of Solar Impulse in the middle of the Pacific, flying only on solar power,” said Bertrand Piccard, a Swiss psychiatrist who is trying to fly around the world using only energy from the sun.

He and his co-pilot André Borschberg began their historic journey in March 2015 from Abu Dhabi in a campaign to build support for clean-energy technologies.

But along the way, something caught their attention. From their experimental aircraft, the Solar Impulse 2, they spotted last month what some call the world’s largest trash dump.

‘I flew over plastic waste as big as a continent’

Piccard was flying above the Great Pacific Garbage Patch. Much of the plastic we use isn’t recycled or buried in landfills, but finds its way to the ocean. There, it breaks down into a hard-to-spot “peppery soup” of tiny microplastics and larger debris.

Worldwide, as many as 5 trillion pieces of plastic now pollute our oceans. These tiny particles look like food to the ocean’s smallest creatures. That means plastics enter the food chain: Fish eat plastics, and humans eat fish, which means that we may be picking up toxic chemicals from ocean debris.

What can you do about ocean debris?

The best way to help is keeping plastic from getting to the ocean in the first place:

  • Find reusable alternatives to disposable plastics.
  • Join a community or beach cleanup.
  • See plastic litter? Snag it before it enters the nearest waterway.
  • Write to your government officials about policies to tackle ocean trash.

Keeping the ocean healthy is vital for the health of the planet. “Above the ocean for three days, you see the waves, sun, clouds, full moon,” said Piccard after landing Solar Impulse 2 in California. “It’s the world I love.”

And that Swiss team? It landed in Arizona this month, the 10th leg of their journey. After crossing the United States, Solar Impulse 2 will head to Europe before finally returning to Abu Dhabi.