If your idea of a fantastic vacation means being near the water, head to Isla Mayor o del Barón. Whatever you choose to do here, you're unlikely to get bored of those lovely views.
If you're planning to go to Isla Mayor o del Barón in San Javier, leave time to check out some other sights too. After you've covered off this water-surrounded land mass, Mar Menor isn't far away and will keep you on the move for a little longer.