A visit to the beach can be a sensory nightmare for an autistic person. I highly recommend sunglasses, a visor, shoes and clothes that easily repel sand and water, and noise reduction headphones to tune out the noise. Even more, plan the day out to make the time there feel less weirdly go-with-the-flow. Schedule your picnic, water time, and moments on the boardwalk. Even more, if you can, choose a beach that you already know and/or is less populated!