Mutriku (Spanish: Motrico) is a coastal town located in the province of Gipuzkoa in the Autonomous Community of Basque Country in northern Spain. It has a population of around 5000 and provides access to the Bay of Biscay. It is the site of the world's first multi-turbine breakwater wave power station, opened July 8, 2011. The Church of San Andrés can be found here, being one of the oldest churches in Gipuzkoa, dating to the year 1080.

Two different spellings are used for the town. Mutriku is the historical name as used by its inhabitants, but Motrico is the official spelling from the 13th century until 1980 on writing. In standard Basque language, the term Mutriku is used nowadays, the Basque spelling becoming official in 1980 by council decision. Since 1989, Mutriku has been the only official name accepted by the BOE, and it is used in modern official documents and in the Spanish-language media across the Basque region.

The town name's etymology has attracted much heated discussion. It is uncertain whether it was created before or at the founding of the town in 1209, although it seems to predate royal foundation as the 13th-century town charter mentions Motriko.

This small town lies on the coast of the Bay of Biscay, in the northwestern corner of Gipuzkoa. It is perched on rocky cliffs by the sea, and low tide reveals many bathing places and fishing spots. The town's beaches are located on the mouths of Deba and Artibai rivers. The name of the dark sand beach at the Deba's mouth is Ondarbeltz (hence the name, literally 'black sand' in Basque), while the beach at the mouth of the Artibai river is light gold in color. At the center of the village and halfway between the two river mouths lies a natural bay with the harbour. From the harbor there is a view of the whole town, dotted with medieval-style buildings.

Apart from the urban centre where the 85% of the population lives, the village contains 9 minor neighbourhoods as follows: Astigarribia, Artzain Erreka, Galdona, Ibiri, Laranga, Mijoa, Mizkia, Olabarrieta and Olatz.

The river Deba is the limit of the town to the east; some small rivulets flow from the village to it as the Olatzgoiko erreka, the Ainoerreka, Jarrolatza erreka and Txokorrekua. On the western boundary lies the Artibai, although in this case the river from city limit is the Mijoaerreka race that leads Saturraran beach in the bay at the mouth of Artibai. The Saturraran forms a small basin that collects water from Olatz and surrounding mountains with rivers: Errekabeltz, Armentxako erreka, Zinoaetxeberriko erreka, Artzainerreka, Aldaberreka, Bidekoaerreka, Ondaberroerreka and Kurpitako erreka. Between these two watersheds, Deba and the Saturraran, another small basin that forms a small river that runs down from Kalbario and the valley which sits the town center and surrounding areas, these are: Errekaundi, Idurreko erreka, Leizarreko erreka, Maldomin erreka, Xoxuarterreka and Lasaoko erreka.

The topography of Mutriku is marked by Mt. Arno (608 m), which rises above the town. It is a mass of limestone covered with oak and native conifer Cantabrian forest. The terrain is very rugged, with steep slopes and narrow valleys extending down to the coastline, cliffs, and tidal region of Guipuzcoa.

Mutriku's economy is tied to the sea. Fishing has historically been the main economic driver, providing the raw material for canning factories. The fishing sector has been greatly affected by the economic crisis; only a few inshore fishing boats remain. Agriculture in the rural districts is for subsistence and local consumption; surplus crops are sold in regional markets. Little livestock is present. Logging in rural areas focuses on insignis pine and other conifers.