Los Arcos is the name given to the three huge rocks just off shore near Mismaloya. The name Los Arcos (The Arches) comes from the arching caves and grottoes that have been carved out by time and the pounding surf.
The area is now a federal underwater park and eco-reserve. It sports some of the best underwater exploring along the coast, and several tours take visitors there daily.
Los Arcos is also the name of the open-air Amphitheater at the end of El Malecon in El Centro, where the original namesake can been seen through the man-made arches that mark the site. Each Sunday afternoon free public performances are given and artists set up their wares.
I got to do a small bit of snorkeling here. Follow up link and I have a seperate Los Arcos page with plenty of pictures of the area in the travelogues.
Los Arcos is one of the places where locals and tourists gather in the evening to listen to music or to admire the clowns. It is a fun place to go to and spend an hour or two while enjoying some fresh fruit or sweets sold by the street vendors.