The Great Pacific Garbage Patch (GPGP) was first noted in the late 1980s, so it’s far from new. However, the latest estimate of its size, published Thursday, is between four and 16 times larger than previous reports: a whopping 1.6 million square kilometres, or 617,763 square miles. The increase is partly down to better surveying techniques, but also more garbage being in the patch.

By way of comparison, Alaska—the largest state in the U.S.—is only 570,641 square miles. The trash vortex is bigger than countries such as Mongolia and Iran, both of which are pretty large.

According to the non-profit organization Ocean Cleanup, whose founder Boyan Slat led the latest research, there’s at least 79,000 tons of plastic in the GPGP, which lies between California and Hawaii.

Most of the pieces in there are microplastics—those tiny particles of plastic that seem to be in most bottled water these days—but they only make up for 8% of the total estimated mass. By contrast, at least 46% of the GPGP’s mass is made up of fishing nets. There’s a lot of other debris in there too, and as much as 20% is thought to come from the 2011 Japanese tsunami.

All this trash is thrown together by the North Pacific Gyre—the largest system of circulating ocean currents on the planet.

The international team of researchers modelled the GPGP through surveys from the air and the sea, over the last three years. They say the pollution in the vortex is “increasing exponentially and at a faster rate than in surrounding waters.”

“To be able to solve a problem, we believe it is essential to first understand it,” said Slat. “These results provide us with key data to develop and test our cleanup technology, but it also underlines the urgency of dealing with the plastic pollution problem. Since the results indicate that the amount of hazardous microplastics is set to increase more than tenfold if left to fragment, the time to start is now.”