Co To District People's Committee said the 7-km stretch of the beach was polluted by pieces of styrofoam, prompting it to dispatch hundreds of people to collect garbage.
The garbage collection takes several days at a time.
Most of the waste comes from seafood farming households in mainland districts who dump it in the water after removing or relocating their fish cages.
It then gets lost in the tides and drifts to the coast of Co To.
In April and May, the waters of UNESCO heritage site and tourist attraction Ha Long Bay in northern Vietnam were filled with trash and styrofoam buoys from seafood farming households. Ha Long authorities launched a months-long campaign to clear up the trash.
Situated around 80 kilometers from the mainland, Co To is famous for its pristine islets and primeval forests. Access used to be strictly controlled due to its proximity to the Chinese border.
In the first seven months of 2023, Co To welcomed about 230,000 visitors, 1.6 times higher than in 2022.