Prince William has recorded a video message in support of the Amateur Swimming Association's (ASA) vision that every child has the right to learn to swim.
An ASA report has found more than half of children aged 7-11 years cannot swim 25 metres.
Jon Glenn from the Amateur Swimming Association said "parents have a role to play as well" as the schools, when encouraging children to learn to swim.
He said: "If families do not swim, it is unlikely that you will take your families swimming as well because you feel uncomfortable, nervous in and around the water, so starting at an early age is really important.
"Once they've learnt those basic skills once you get to school and you have those lessons you can really pick up the strokes a lot quicker."
Prince William has recorded a video message outlining importance of teaching children to swim.
It follows a report by the Amateur Swimming Association (ASA) which shows more than half of children aged 7-11 years cannot swim 25 metres unaided.
"Swimming has always been important to me," the Duke of Cambridge said. "Swimming is unique, it is the only sport that can save lives, which is why I'm so keen for school swimming to be accessible for all children at all primary schools."
He added: "The ability to swim changes lives, it brings huge joy and it can keep us fit and healthy. But above all, it can keep us safe, which is why I'm pleased to lend my support to this campaign."