Volunteers fish plastic out of a canal as they take part in the annual Kings Fishing to make the canals plastic-free again.

Equipped with fishing rods and thick gloves, a group of people peers into the water from one of the many boats that line Amsterdam's famous canals.

But it's not fish they're hunting on their cruise along one of the Dutch capital's most famous tourist attractions -- it's plastic.

"It's a completely other way of visiting Amsterdam," plastic Whale founder Marius Smit told AFP.

"Obviously you're on the beautiful canals of Amsterdam in a really nice boat, but at the same time you're active as well, and you add something positive to the canals and to the city because you're making it cleaner."

Pineapples and shoes

On a hot summer's morning, seven people are lined up on the bright green boat decorated with smiling whales.

A group of people peer into the water from one of the many boats that line Amsterdam's famous canals.

Angela Katz, an Australian who has lived in Amsterdam for just over a year, is on her second tour, after learning about the cruises through Facebook.

"I really enjoyed it but also it's really eye-opening just how much rubbish there is in the canals," said the 51-year-old graphic designer, fishing rod in hand.

'Tourists aren't careful'

Plastic in the sea, rivers and other waterways is a problem around the globe, causing harm to marine ecosystems.

Just how much plastic is in the canals of the city dubbed the Venice of the North is hard to estimate, but solutions are easier to find.

"Tourists aren't careful," says Angela Katz as she stands in front of a pile of rubbish.

"So before you know it there is a lot of waste on the streets, then it begins to rain or the wind begins to blow and it rains or blows into the canals," he says.

Agence France-Presse