The Mar Menor plays a crucial role in the story of San Javier The history of San Javier, as is the case of other municipalities in this area, is influenced to a huge degree by its location on the inland shore of the Mar Menor, the largest saltwater lagoon in Europe and one of the most instantly recognizable geographical areas of Spain The geological origins of the Mar Menor lie in the Tertiary Era, between 65 million and 1.7 million years ago..