Hundreds of young Egyptians, including actress Mai El Gheity, trudged through the mud on the banks of the River Nile to collect tons of old plastic bags, bottles and other rubbish.
The teens and twenty-somethings also climbed into boats to reach trash floating through the center of Cairo during the "Youth for the Nile" clean-up - a program backed by the government and other groups to raise awareness of pollution.
Volunteer Dai Soliman worked on as people watched from a bridge.
"Those people above looking at us must have thought that they threw something in, and now there are some people who are collecting their garbage. So this is awareness, it is direct awareness in action," she said.
The teams, most wearing the scheme's white boots and blue and yellow gloves, collected three to four tons of waste on Saturday, the environment ministry said.
A report issued last year by government's Egyptian Environmental Affairs Agency said 150 million tons of industrial waste end up in the Nile every year.
Similar clean-ups are scheduled in Luxor, Aswan, Assiut and other provinces through the rest of the year.
