One useful word which says that there are no people somewhere, or very few, especially in a place where people are sometimes expected to be, is deserted. The proper meaning is that there is nobody there. However, it is also used when there are only a few people somewhere, in an exaggerated sense. For instance, suppose we are on a street with many restaurants on a busy night, such that most of them are full, and we see a place with people seated at only one table, with seven other tables empty. The natural thing to say is "Look, that place is deserted!" or "there's nobody in there", which isn't factually true.
"Deserted" is neutral; it is positive or negative based on the context. "Let us find a deserted beach where we can be alone".
Places that are deserted habitually are isolated, abandoned, uninhabited, solitary, vacant and so on; all such words have a different nuance of meaning.
"There are sandy, isolated beaches." is not a bad way to express your sentence.