Itzurun, Golden sand urban beach in Zumaia, Spain.

Itzurun, also called San Telmo, is a 270-metre sandy beach north of Zumaia's old town, between the points of Marianton and Algorri. Vertical flysch cliffs up to 150 metres high stand behind the sand, whose layers of sediment lie almost upright. The beach faces west toward a wide view of the Biscayan coast as far as Cape Matxitxako; to the east lies the small stone beach of Itzuruntxiki.

The International Union of Geological Sciences designated the rock outcrops at Itzurun as the global boundary stratotype sections for the bases of the Selandian (~61.6 million years) and Thanetian (59.2 million years) stages of the Paleocene. Itzurun and Meishan in China are the only two sites worldwide with two golden spikes. The vertical flysch layers record these geological boundaries.

Itzurun is also known as San Telmo beach, and the rocky shore at its eastern end is called Itzuruntxiki, while the area on the left is known as Santelmopea. The beach has appeared on screen in Ocho apellidos vascos and Game of Thrones, and the Basque name Itzurun is the one used locally.

The beach is easy to reach on foot from the center of Zumaia, and parking is available close by. Showers, restrooms, and lifeguard service are on site during the summer season.

The cliffs around Itzurun were used as a filming location for Game of Thrones, which brought the beach to the attention of many viewers who had never heard of Zumaia before. Fans of the series often walk the shoreline looking for angles they recognize from specific scenes.