Not my coast but a quick search on google should help, and I am sure you will get all your questions answered on the forum. Below a link and a little help to get you started.
http://www.viva-murcia.com/san_javier_p149.php
San Javier - Costa Calida - Murcia - Spain
Perhaps best known for being the home of Murcia’s airport, San Javier is a small town on the Mar Menor coastline of the Costa Calida, Spain. Named after the apostle Saint Francis Xavier, the municipal district of San Javier covers an area of some 74 km2 and has a permanent population of around 23,000 (which rises considerably during the busy summer months).
The region around San Javier is very important for agriculture and a wide range of produce is grown there. In recent years it has also become very important for tourism, the Mar Menor (Lesser Sea) being a huge draw for tourist due to its warm waters and safe beaches. The golf and water sports facilities also contribute greatly to its popularity.
The municipal district of San Javier consists of 8 boroughs and these are Santiago de la Ribera, La Manga, El Mirador, Roda, La Grajuela, Pozo Aledo, La Calavera and Los Saez de Tarquinales.
Though the documented history of San Javier only goes back to the Arab occupation of the area, it is thought that there were settlers there as long ago as the Neanderthal Period. The Phoenicians also sailed these waters and founded settlements along the coast, relics found in the Mar Menor, indicate that both Greek and Roman ships laid anchor in the area.
The region around San Javier became important for both fishing and agriculture during the Arab occupation (8th to 13th Centuries), and irrigation systems put in by the Moors, enabled previously barren land to be planted and harvested. The Arabs also brought with them, their unique fishing methods, some of which are still used today, including the use of reed fences for the trapping of fish, mostly used in the calm waters of the Mar Menor.
The region was re-conquered by the Christians in the 13th Century by Alfonso X (‘Alfonso The Wise’), and the area became somewhat depopulated, recovering slowly over the ensuing centuries. During the 14th to 17th Centuries the surrounding coastline was constantly raided by Berber pirates and a number of defensive towers were constructed by Felipe II to counter these attacks. San Javier became an independent municipality on 9th March 1836.
San Javier today is a busy little town, with a good range of shops, bars and restaurants and the area boasts some of the finest beaches in the region, the renowned healing mud baths at Lo Pagan are just a short drive away.
Definitely worth a visit whilst in San Javier is the ancient city of Cartagena, with its rich history and wealth of interesting archaeological monuments, many dating back to Roman times. The region’s capital, Murcia would also be on the agenda for a visit. Other nearby resorts include San Pedro del Pinatar, Los Alcázares and Santiago de la Ribera.
San Javier is located on the N332 coast road and is easily accessed from the AP-7 motorway. The airport which serves the city of Murcia is just a 5 minute drive away from the town itself.