In London, crowds took a knee outside the US Embassy before marching to Westminster.
Lizzie Carr's Plastic Patrol is aiming to clear over a million pieces of rubbish from the city's waterways by the end of the year.
"YOUUUU ESSSSS AYYYYY!"
We spoke to the organisers about why the event has moved from just south of the river in Vauxhall Pleasure Gardens to Haggerston Park.
It's (still) coming home.