CAESAREA, Israel (AP) — Divers visiting the ancient seaport of Caesarea on Israel’s Mediterranean coast occasionally find treasure, but on Friday they searched for trash.

Twenty six scuba-diving volunteers removed around 45 kilograms (100 pounds) of garbage from between the sunken pillars and submerged ruins of the historic site of Caesarea Maritima as part of a United Nations World Oceans Day initiative.

Dozens more at sites along Israel’s Mediterranean coast and on the Red Sea reefs in the Israeli resort of Eilat removed more than 150 kilograms (330 pounds) of trash. The cleanup included bottles and bags, ghost nets, fishing lines, aluminum cans, lost towels and other odd items, including a beach lounger, that were polluting coastal waters.

The events were organized by the Israeli Diving Federation with support from the Environmental Protection Ministry and Nature and Parks Authority, which manages the coastal areas, including Caesarea’s Roman-period port. 

The U.N. marked World Oceans Day on Wednesday, but the scuba diving volunteers were taking to the water to clean the sites on Friday and Saturday, Israel’s weekend.

The U.N.’s environment program says the equivalent of a garbage truck full of plastic is dumped into the ocean each minute. Plastic waste can take centuries to degrade, and causes extensive damage to marine ecosystems.