
A bizarre green seaweed has swamped the beaches of one of mainland China’s most popular seaside tourist destinations.

But happy-go-lucky tourists at Qingdao, in eastern Shandong province, are determined not to let the other-worldly algal bloom put a dampener on their fun.

The seaweed has transformed the golden beaches into verdant meadows every July since 2007, and local authorities are beginning to develop a range of uses for the green gloop.

Washing in from the Yellow Sea, the ‘green tide’ of Ulva prolifera is still somewhat of a mystery in the scientific community.

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Green tide: A young boy plays in the algae that covers beaches in Qingdao, in Shandong province, eastern China

Holidaymakers make the most of the slime-covered beaches, in Qingdao, one of China's most popular seaside tourist destinations

Two young boys cover themselves in the Ulva prolifera algae, which has proved something of a mystery for the scientific community

The beach-goers treat the seaweed, which has covered the coast every July since 2007, like a play thing, frolicking in the slime

Many theories blame the phenomenon on climate change and industrial pollution, with warm summer sea temperatures contributing to the algae’s rapid growth.

Coastal pollution from fertiliser runoff and sewage provides the algae with nutrients including phosphates and nitrates.

But others point to the expansion of seaweed farming along the coast as a possible culprit.

The foul-smelling, bright green algae helps Qingdao live up to its name, which translates as ‘Green Island’.

Now in its ninth year, the tide of thick slime nearly caused havoc at the Beijing Olympic Games in 2008, when Qingdao was chosen as the venue for the Olympic sailing events.

Some theories blame the algae invasion on climate change and coastal pollution, although others blame a rise in seaweed farming

Warm summer sea temperatures provide an ideal breeding ground for the algae, while pollution provides phosphates and nitrates as a food source

Thousands of military staff, volunteers and workers are drafted in every year to help with the enormous clean-up operation

Every year, around 20,000 tonnes of the seaweed have to be cleared off the beach by thousands of helpers

Local authorities have found some uses to take advantage of the algae, which can be dried and used as animal feed or fertiliser

Children play and splash in the algae, which for some is a welcome change from the kilometres of golden beaches

Families flock to the beaches, one of mainland China's most popular seaside tourist destinations, to get away from the cities in the summer months

The thick slime nearly caused havoc at the 2008 Olympic Games, which were held in Beijing, as Qingdao was chosen to host the sailing events

The invasion of thick slime turns the Yellow Sea green throughout the summer months, arriving between mid-June and late July

The scientific community can't agree what causes the algae, which has been invading for nine years, but is generally not harmful to humans

Although it is not generally harmful to humans, in large quantities it can prove dangerous as it decomposes, producing toxic hydrogen sulphide gas.

The thick layer of algae, known as hutai in Mandarin, can also asphyxiate marine life by sucking oxygen out of the water.

In 2013, the ‘green tide’ covered more than 7,500 square miles of coast – an area almost the size of Wales – and the army had to be brought in to help with the clean-up.

More than 10,000 volunteers and 1,000 soldiers cleared 20,000 tonnes of the slime out of the sea.

Authorities have the seaweed taken to processing depots, where it is dried and processed into animal feed, fertiliser or a medicinal supplement known as hutai sugar, which is said to help lower blood sugar.

A study published in May 2013 in the journal Estuarine, Coastal and Shelf Science, concluded the algae originates from the Jiangsu coast before being swept north towards Qingdao.

Scientists from the Yantai Institute of Coastal Zone Research cited satellite images and field observations as the basis for the theory.

In 2013, the 'green tide' covered more than 7,500 square-miles, an area almost the size of Wales, and required a huge clean-up operation

Tractors, trucks and volunteers are brought in to help clean the algae of the beaches, to be taken to processing depots

The algae has become almost a tourist destination in itself, and it so photogenic it's a favourite on social media sites

Some scientists believe coastal pollution from fertiliser runoff and sewage provides the algae with nutrients including phosphates and nitrates

Estimates claim around 20,000 tonnes of the green slime is cleared off the beaches during the summer months, in the annual 'green tide'

Children find new uses for the green slime, throwing it at each other, filling buckets with it, and burying themselves

Thousands of people flock to the beaches every year for their holidays, despite the annual invasion of the 'green tide'

A study published in May 2013 in the journal Estuarine, Coastal and Shelf Science, concluded the algae originates from the Jiangsu coast before being swept north towards Qingdao

Washing in from the Yellow Sea, the ‘green tide’ of Ulva prolifera is still somewhat of a mystery in the scientific community