When researchers flew over the swirling mass of trash known as the Great Pacific Garbage Patch for a closer look, they weren't expecting it to be pretty. But what they found suggests the massive collection of discarded nets, garbage, and plastics floating in the middle of the Pacific Ocean might be even worse than they previously thought.

The patch has been steadily growing in size and density over the last few decades. Despite the scale of the problem, however, there had not been any aerial survey of the heart of the patch until now.

The mission was partially funded by the Dutch Government, and led by The Ocean Cleanup, a foundation dedicated to developing methods to rid the oceans of plastic pollution. Ocean Cleanup researchers have previously mapped the patch using a fleet of boats but found that the conventional boat-based method for measuring ocean plastic yielded inaccurate results. So they decided to take to the sky.

"In order to solve the plastic pollution problem, it is essential to understand its dimensions," said the organization in a blog post. "Knowing how much and what kind of plastic has accumulated in the ocean garbage patches is especially important. This determines the design of cleanup systems, the logistics of hauling plastic back to shore, the methods for recycling plastic, and the costs of the cleanup."

Using a modified C-130 Hercules aircraft, the expedition flew low over the heart of the patch, expecting to make a visual count of large pieces of debris, assisted by sensor data. But they soon found that the density of materials in the patch was much larger than they had anticipated.

"Normally when you do an aerial survey of dolphins or whales, you make a sighting and record it," Boyan Slat, the founder of the Ocean Cleanup, told The Guardian. "That was the plan for this survey. But then we opened the door and we saw the debris everywhere. Every half second you see something. So we had to take snapshots – it was impossible to record everything. It was bizarre to see that much garbage in what should be pristine ocean."

The team counted more than a thousand items that appeared to be more than a half a meter in size over the course of 2.5 hours.

Most of the items floating in the Great Pacific Garbage Patch are made of plastic, which does not biodegrade like other trash items do. Instead, plastic breaks down into smaller and smaller pieces and are often consumed by the smallest marine life. The plastic then works its way up the food chain, causing problems for fish and even for the humans that consume them. According to a study published in February of 2015, anywhere from 4.8 to 12.7 million metric tons of plastic was dumped into the ocean in 2010, and that amount has likely increased since then.

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The Ocean Cleanup Project is set to conduct further aerial surveys in preparation for the development of their ambitious plan to begin plastic cleanup. In 2020, the foundation hopes to deploy a 100-km (62-mile) V-shaped boom to capture junk from the patch. There is a lot of work to be done before the boom can be deployed, but the organization hopes it will be able to clean out ocean plastic on a scale never before seen in human history.

"Everything is unknown so everything is a potential problem," Lourens Boot, the program’s chief engineer, told The Guardian in November of last year. "The risk matrix is big, but one by one we are tackling those risks."