Alt Maresme, Subregion in Maresme, Spain

Alt Maresme is a non-administrative subregion of the Maresme comprising twelve municipalities, from Arenys de Mar to Tordera, covering 255.01 km². It is bounded by the Riera de Caldes, the historical border with Baix Maresme, and includes the Turó Gros in Sant Iscle de Vallalta, which rises to 798 m. The Montnegre i el Corredor Natural Park lies within its territory.

From 1303 to 1833 Alt Maresme belonged to the diocese, county, vegueria and corregiment of Girona. The provincial division of 1833 detached it from Girona and attached it to the province of Barcelona, but the Arenys de Mar judicial district was created to keep the Girona diocese's particularities in judicial matters. Since 1980, 2005 and 2007 attempts have been made to return the area to Girona.

The name Maresme comes from the marshes created by the area's streams, the rieres, as they carry water down the valleys. The Turó Gros in Sant Iscle de Vallalta reaches 798 m, while hills such as the Turó d'en Ventveió in Canet de Mar stand around 300 m. The Montnegre i el Corredor Natural Park marks much of the territory.

The historic boundary with Baix Maresme runs along the Riera de Caldes, and the Montnegre i el Corredor Natural Park covers much of the inland terrain. The longest watercourses crossing the subregion are the Riera d'Arenys, the Riera Gavarra at Canet de Mar, the Riera de la Vallalta at Sant Pol de Mar, the Riera de Capaspre, the Riera de Pineda, the Riera de Santa Susanna and the Tordera river.

Each municipality falls under a complex administrative arrangement where local courts report to the Arenys de Mar judicial district while healthcare falls under Girona. This uncommon administrative split reflects how old jurisdictional boundaries remain layered across modern systems.