The world's biggest coal terminal was closed Saturday by hundreds of protestors calling on Australia to stop exporting coal, reported dpa.
The blockade prevented coal carriers entering Newcastle, located a two-hour drive north of Sydney.
Paddling kayaks and craft made from milk crates and inflated inner tubes, the protestors urged Australia, the world's biggest coal exporter, to switch to less polluting sources of energy.
"These people sent a serious message that the government, if they are going to be serious about climate change, they must address the coal industry," Greens parliamentarian Lee Rhiannon said.
"It's the fourth time this blockade has been held and each time it attracts plenty of support and we will continue with future peaceful actions if we think it's necessary."