Debabarrena (English: Lower Deba) is a comarca located in Gipuzkoa, Basque Country (Spain). It has an area of 180,3 km². It is north from the comarca of Debagoiena, east from the province of Biscay, and south from the Gulf of Biscay.
The municipalities which compose Debabarrena are Eibar, Placencia de las Armas, Elgoibar, Mendaro, Deba and Mutriku. Eibar is the biggest one with about 28,000 inhabitants. The second biggest one is Elgoibar, with about 11,000 inhabitants, and the other municipalities have less than 10,000 citizens.
Debabarrena is surrounded by many mountains, which are not very high. The higher ones have a height of around 800 metres. Urko (791 metres), Arno (612 metres) and Andutz (610 metres) are the highest ones. All the region is full of forests and prairies, and also has many streams, most of them tributaries of the Deba river, which names the comarca. These streams are usually short and have a high level of contamination, despite the fact that the level of contamination has been reduced considerably since the 1980s.
Debabarrena is located in the centre of the Basque Country, which benefits the region's communications. The main highway is the AP-8, which connects Debabarrena with Bilbao and the French border, but also the AP-1, which connects Eibar with Debagoiena and Álava.
The railway line that communicates Bilbao and San Sebastian is also used in Deba, Mendaro, Elgoibar and Eibar mainly as a short-distance train. The harbours of Deba and Mutriku are not used for goods and passengers.