Pet owners who bag up dog poo and leave it on beaches are threatening the safety of people who visit the seaside.
A new survey shows an overall increase of 11% in dog mess on UK beaches - it's gone up 71% in Scotland.
Dog poo is dangerous because it contains high levels of bacteria - if it gets into water it can be very bad for bathers' health.
Almost 4,500 volunteers took part in the survey by The Marine Conservation Society - across 335 UK beaches.
The society says that pet owners have been thinking ahead by carrying plastic bags to clear up dog mess - which is a good thing.
But it now wants to encourage them to take the bags off the beach and bin it in one of the many dog bins provided.
Even though levels of dog poo were up, there was some good news: overall litter levels were down this year.