A group of men from Pontypool continued drinking after the RNLI rescued them from the sea.
The "intoxicated" men were seen drinking alcohol "through funnels" before police ordered them to leave Ogmore-by-Sea on Saturday April 24.
Police officers seized their alcohol and the group will receive an anti-social behaviour warning letter.
The men, three aged 19 and one aged 20, had been helped out of the sea by RNLI crews before continuing to drink alcohol on the grass near the Rivermouth car park.
It comes as South Wales Police increased patrols in coastal areas of Cardiff and the Vale of Glamorgan at the weekend to tackle anti-social behaviour at beauty spots.
At around 8pm on Saturday, a 19-year-old man was arrested for carrying a knife on Penarth Esplanade. The man, from Rumney, said the knife was for fishing purposes but had no other fishing equipment with him.
He was taken into custody for interview and received a caution.
South Wales Police Chief Inspector Bella Rees said: "The vast majority of people who visit our beautiful coastal areas behave appropriately and in accordance with the regulations. But we will not tolerate the behaviour of a minority who consume excess alcohol, litter and ruin the quiet enjoyment for law-abiding citizens."
There have been other incidents at Ogmore-by-Sea throughout the pandemic. Last summer there was a mass gathering and brawl on the beach during lockdown. Police detained two men in their 20s and dispersed the crowds.