The database on maritime boundaries in the EU was created in 2014 by CETMAR for the European Marine Observation and Data Network (EMODnet). It is the result of the aggregation and harmonization of datasets provided by EEA ( https://www.eea.europa.eu/) and Marine Regions ( http://marineregions.org/). It is updated every year and is available for viewing and download on EMODnet Human Activities web portal ( https://emodnet.ec.europa.eu/en/human-activities). The database contains polylines representing maritime boundaries (territorial waters, bi- or multi-lateral boundaries (e.g. in the North Sea) as well as contiguous and exclusive economic zones) in the following countries: Belgium, Bulgaria, Croatia, Cyprus, Denmark, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Malta, Netherlands, Poland, Portugal, Romania, Slovenia, Spain, Sweden, UK and third countries related to them. Each polyline has the following attributes (where available): MBLSZOTPID, LocalId, Site Name, Legal Foundation Date, Legal Foundation Document, Country, nationalLe, Nomenclature of Territorial Units for Statistics and Type of Agreement. For the case of the Coastline database, the following attributes are included (where available): FID_Europe, Shape_Leng, Source, Shape_Le_1, Shape_Le_2.