People have been standing near cliff edges and posing for pictures prompting warnings from patrolling coastguards.
Large numbers of visitors travelled to the south coast on Monday and pictures from Birling Gap in East Sussex show people standing on the chalk cliffs.
The Maritime and Coastguard Agency said it was "more important than ever" to stay away from the crumbling coastline.
"Coronavirus hasn't gone away and your choices might put our frontline responders at risk," it said.
"We really can't stress enough how important it is to keep back from cliff edges, There is no 'safe' place to be and the cliffs along the UK coastline are continuously eroding. "
Rescue teams have been deployed to beaches, cliff and marinas across the country to "look out for anyone in trouble and offer safety advice where needed," the agency said.
It said its pre-emptive measures were especially important while RNLI lifeguards provide a limited service due to coronavirus.
On Sunday a young girl was pictured peering over the edge at Birling Gap, prompting Wealden District Council to urge people to stay away from the cliff edge.
The council tweeted: "Is it really worth risking your life for?"
There have been significant cliff falls along the south coast in recent years.
At Seven Sisters, near Eastbourne, 50,000 tonnes of the cliff crumbled and fell to the beach below in 2017.
The following day a 23-year-old South Korean tourist fell to her death when she jumped in the air for a picture and lost her footing on the edge.