Litter including babies' nappies, sanitary towels, discarded toys and takeaway packaging are among the items being discarded on Barry Island beach, according to residents.
Vale of Glamorgan council increased the number of bins, clean-ups and public announcements after an outcry last May.
But residents have said people are still leaving their mess behind.
And over the Easter weekend a community litter picking group was kept busy cleaning up after visitors.
Swimmers have also been been helping by bringing debris to shore.
"It leaves you despondent. The council can only do so much," resident and council worker Joanne Cheek said.
She said the beach was "immaculate" each morning as it was "picked and raked" before people arrive.
"The majority of it is always plastic and food packaging. The thing I think frustrates most people the most is the wet wipes, nappies, sanitary towels, and that people bury things within the sand," she said.
"We just want them to take their litter off the beach and use the bins that are provided. They are in every car park, are along the promenade. There's no reason for people not to be using a bin."
Ms Cheek is also a member of the Beautiful Barry Facebook group whose members regularly take part in clean-ups.
Fellow member Matthew Lock wrote: "Despite our best efforts a lot of the rubbish was being taken out to sea. We asked this swimmer to go grab it for us."
Swimmer Ryan Price, who collected some of the rubbish that had floated out to sea, said: "For the love of God I wish people would take their rubbish up to the bin."
The council has been asked to comment.
Daytrippers were accused of showing a "complete disregard" for Barry Island over last year's early May bank holiday during the record-breaking hot weather.
Then, the council said "unprecedented quantities of rubbish" were thrown away, much of which was washed out to sea when the tide came in.
In response, it increased the number of litter bins and co-ordinated litter picks.