Well, it's hard to say for sure. It might draw inspiration from real-life incidents but could also be entirely fictional. You'd have to look into the background and the author's intentions to know for certain.
Yes, 'The Beach Bum' is somewhat based on a true story. It draws inspiration from real - life beach - bum cultures and the laid - back lifestyles often found in coastal areas.
Yes, some Australian beach horror stories are based on true events. For example, there have been shark attacks on beaches which are truly terrifying incidents. These real - life events often form the basis for horror stories set on the beach.