The quality of the water at UK beaches has fallen for the first time in eight years, an annual study has warned.
People working on the Good Beach Guide said the number of beaches failing water tests has doubled since 2003.
Marine Conservation Society spokesman Thomas Bell said the wet weather last summer made things worse and they think fewer beaches are safe for swimming.
He said the large amount of rain washed lots of rubbish into the sea, making it much grubbier and more polluted.
The guide recommends 427 of the UK's 800 beaches, down from 453 safe beaches last year, which is the first fall since 1997.
On Thursday the European Commission praised the UK for the quality of the water around the beaches.
But the MCS "wouldn't advise" swimming at beaches which have failed water quality tests.