Except for the official Airport and Ship Ports all shores and waterways are public domain and accessible to the public.
When private property borders the shoreline (beach), the following right is applied. All land strips from the waterline up to ten meters into the shoreline is public.In fact there is no single private property that borders the waterline in Aruba.
So even though you might have resort hotels bordering the shoreline (beaches), you have the beach right from the waterline up to 10 meters into the shoreline.You can bring your beach chair and jug, with food and beverage, and spend your day at the beach with your family.The hotels would welcome patrons to their food and beverage services. However it does not give you the right to use the infrastructure of the hotels, unless they agreed to it. For example if they have beach chairs, you do not have the right to use it.
The saying that goes" when you have it, you take it for granted" is true for beach use in Aruba. The beaches in general, including the weekends, are scarcely populated.The beaches are more populated mostly during the week before and after Good Friday, when, by tradition you have more locals visiting the beaches.
There are many beaches to choose from. You could be at the hotel areas, at Palm Beach and Eagle Beach, where there are more infrastructure or you could be more secluded on beaches like Arashi, Baby Beach and Boca Catalina.