The group, which made headlines earlier this month when several members climbed onto the roof of the Scottish Parliament, says low-lying Leith will become a victim of regular flooding by 2050 if action against sea-level rise is not taken.
XR told reporters to “expect inflatables, boats, snorkels, swimwear and flippers” at their 1:30pm demonstration.
The group hopes to draw attention to the global threat posed by widespread flooding too.
In a report published last year, experts estimated that 230 million people around the world live on land less than 1 metre above high tide levels - and around one billion on land less than 10 metres above high tide levels.
Meg Peyton Jones, a biology student at the University of Edinburgh and XR supporter, said: “The climate crisis has already displaced millions around the world, often due to flooding which destroys people’s homes, livelihoods and safety.
“This should be enough to make our governments act now. However, as they set targets decades in the future, while continuing to encourage maximum economic recovery of fossil fuels, we remind them that disaster is a very real threat to people in Edinburgh too.”
Ahead of the demonstration, Chief Inspector Scott Richardson, of Police Scotland, said: "We are aware of planned protest activity due to take place in Edinburgh on Saturday, 17 October, 2020.
“Appropriate policing resources will be deployed to maintain the safety of the public and minimise disruption to affected communities.”