It's hard to gauge the health of an ocean out in the ocean. But where the water meets the shore, the dirty truth is revealed. That is what volunteers in 76 countries around the world discovered last September.

A report by the Ocean Conservancy released last week details nearly 7.2 million items that were collected by volunteers on a single day last September as they combed beaches and shores. After cleaning 33,000 miles of shoreline, six million pounds of trash was collected and catelogued. That worked out to an average of 16 pounds of trash per volunteer. More chilling, that means that the 378,000 volunteers on average collected 182 pounds of trash for every mile of shoreline

Volunteers in the U.S. collected 390 pounds of trash per mile, among the highest rates of any country, while collectors in neighboring Canada collected 74 pounds per mile and those in Mexico, 157 pounds per mile, according to the report. (The high number in the U.S. also reflects the large number of U.S. volunteers who took part, according to an Ocean Conservancy spokesman.)

Read more about the cleanup and about this year's project here. Or check out the raw data detailing the items collected in five worksheets which can be viewed by item, state, and country breakdowns -- or any combination of those -- here.

Photo: Courtesy of Ocean Conservancy.