Surfing classes for autistic children are threatened by a lack of funding.
The surf lessons for youngsters at Caswell Bay near Swansea have been labelled a "lifeline" for children often excluded from activities.
But funding runs out in a few weeks, leading to fears that the lessons will be available only to families who can afford them.
Autism organisation Spectrum said funding must be found to help children continue the "unique" classes.
Spectrum chair Anna Parton said: "In early September, our bank account runs completely dry.
"All the children love it so much that we will continue running as a group but what will happen... is that our group becomes a group only for people who can afford it.
"We've got to find this money from somewhere. We have found something which is unique, something that the children love.
"This is a group of kids that get excluded from so many different aspects of life and society that we have to make this work."
Ms Parton added that the surf school had been "an amazing experience".
"Looking for activities for our children has been a challenge. As much as many group activities do say they welcome children with autism and all disabilities, if you speak to any parent of an autistic child they will tell you something very different," she said.
"There is an awful lot of judgement out there - people will make assumptions about our kids and so it's very easy to get to these activities and feel excluded.
"They really enjoy it and, for my son, this has been a lifeline.
"He looks forward to it so much. It's one of the things in his life at the moment which is going really well."
Gower Surf Development instructor Ben Clifford said autistic children often had an aptitude for the sport.
"The main thing is to remember to be very specific in your instructions and address the children as individuals as much as you can, rather than as a group," he said.
"It's so good to see them. They are doing things that they normally can't do.
"They don't give up, they keep going, which is a big thing for autistic children."