Boaters Mapping Floating Garbage Patch In North Pacific Return To San Francisco

SAN FRANCISCO (CBS/AP) -- Scientists and volunteers who have spent the last month gathering data on how much plastic garbage is floating in the Pacific Ocean say most of the trash is medium to large-sized pieces, as opposed to tiny ones.

Volunteer crews on 30 boats have been measuring the size and mapping the location of tons of plastic waste floating between the West Coast and Hawaii.

Three of the boats, including a 171-foot mother ship, returned to San Francisco on Sunday.

Researchers say they hope to test out a 1-mile barrier to collect garbage near Japan. The ultimate goal is construction of a 60-mile barrier in the middle of the Pacific.

"The goal was to take more samples in 3 weeks time than in the past 40 years combined," Ocean Cleanup Project Boyan Slat said.

The boats went on a 30-day voyage as part of the "Mega Expedition" of what's known as the Great Pacific Garbage Patch.

"Based on what we've seen out there, really the only way to describe the The Great Pacific Garbage patch is as a ticking time bomb," Lead Oceanographer Julia Reisser said.

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