In Australia, the next time you order a drink with a straw, a growing number of people want you to think about what happens to that plastic tube once you're done. Environmentalists say the world's oceans are being choked with plastic, which is killing marine life. In Australia, one group is diving into a unique program to reverse that trend. We want to warn you that some people may find parts of the following video disturbing. Greg Navarro brings us the story.

On a sun-drenched Saturday at Sydney's Manly Cove, an army of volunteers suited up for battle. After a brief review of the strategy, they ventured into the water to find and remove the enemy.

"I've got one straw."

HARRIET SPARK FOUNDER, OPERATION STRAW "A friend and I used to come out here snorkelling a lot and we would find hundreds and hundreds of plastic straws in this tiny bay."

So Harriet Spark founded Operation Straw, focussed on ridding the area of a single use object that most people take for granted.

"If you want, we are going to sort the data out soon."

She also mobilised dozens of people willing to give up their Saturday mornings to clean up the cove.

HARRIET SPARK FOUNDER, OPERATION STRAW "Plastic in our oceans is one of our oceans biggest threats, it takes hundreds and hundreds of years to break up - we call it break up because plastic never breaks down and doesn't biodegrade - it breaks up into tiny, tiny pieces and is consumed by animals throughout our food chain."

It's estimated that billions of plastic straws are used around the world every day.

GREG NAVARRO SYDNEY "In the US alone, if you took all of the plastic straws that are used and discarded in just one day, you'd have enough to fill more than 125 school buses."

Their impact on marine life, highlighted in this video, can be tough to watch.

"You can see these ones here are McDonald's straws, they are very distinctive."

Operation straw is also focussed on getting restaurants to take more responsibility. This one now gives customers a stainless steel option.

THOMAS SCHOEB HEMINGWAY'S MANLY "People see the good in it, using metal straws, the only ones we have to remind are the kids not to bite on them."

On this day, these water warriors celebrated a small victory and vowed to continue to battle.

SIMON MALLENDER VOLUNTEER "We can't just fill the ocean full of trash and leave it behind - we have to do something."

Despite being outnumbered by a plastic opponent. Greg Navarro, CGTN, Sydney.