This comment should not discourage more answers (clearly many cultures enjoyed the beach in different ways), but you can find some previous similar answers below:

/u/DarthPositus answers "Did ancient people go to the beach" focusing on the Roman resort city of Baiae in the Late Republic.

/u/LaoBa answers "Did ancient peoples 'go to the beach' as we do today?" focusing on Polynesians surfing at least as far back as the 15th century.

/u/thesoulphysician answers "When did ''going to the beach' become a popular recreational activity?" with a broad answer on the roots of modern beach going with some art history thrown in.