I live in a costal beach town along the east coast of New South Wales Australia, and the other day we were swimming and body surfing the waves and I thought and said to my mate 'do you think aboriginals ever swam at the beach and body surfed waves 30,000 years ago?' I don't know why but it's very hard to imagine!
If you want to know about 30 000 years ago, you might do better to ask this question in r/AskAnthropology. That's before there were written records for historians to study.
hi! not discouraging other responses, but you may be interested in a few earlier posts
Going to the beach
When did "going to the beach" become a popular, recreational activity?
When did "going to the beach" become a popular way to spend time?
Surfing