More than 500 people gathered at Sizewell on the Suffolk coast to highlight the impact a new nuclear power station could have on the beach.
The turnout was double what the organisers had been hoping for.
Those against Sizewell C formed a human wall in front of the site along the line of the proposed sea defences.
They wanted to demonstrate how much of the beach they believe would be buried under rock armour and lost forever.
The group Stop Sizewell C said it was the first time since the pandemic began that protestors had been able to gather in large numbers.
EDF proposes building a twin nuclear reactor at a cost of £20 billion pounds. As part of their plans they say they’re putting in measures to mitigate the impact on wildlife, including recreating habitats like the wetlands nearby.
Business leaders say the new power plant would be a huge boost to the local economy, creating tens of thousands of jobs.
EDF Energy says the new power station will also be important in tackling climate change.
They say by generating electricity from Sizewell C rather than by burning fossil fuels, nine million tonnes of carbon will be prevented from being emitted into the atmosphere every year.