Ria Formosa Catamaran Tour with Visit to Two Islands A chance to explore Ria Formosa Natural Park from aboard a catamaran 80% liked it from 5 reviews Instant confirmation Tickets and prices See tickets and prices On this catamaran tour of Ria Formosa Natural Park, you'll have a chance to explore its islands and take in its stunning natural beauty. The protected area is consisted of of sand dunes, salt marshes, barrier islands and a lagoon. To begin your tour, you'll disembark at the unpopulated Deserta Island. While there, your guide will show you some of its native wildlife and also take you to the Cape of St. Mary, which is Portugal's southernmost point.