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San Marino
Location
CountryItaly, San Marino
Physical characteristics
Source 
 • locationSan Paolo Mountain
 • elevation864 m (2,835 ft)
MouthMarecchia
 • location
Torello, frazione of San Leo
 • coordinates
43°57′48″N 12°23′51″E / 43.9632°N 12.3975°E / 43.9632; 12.3975
Length8.7 km (5.4 mi)
Basin features
ProgressionMarecchiaAdriatic Sea

The San Marino (Italian: Rio San Marino) is a river in the Italian peninsula. It flows through San Marino (Chiesanuova and Acquaviva), then north into Italy. For some of its length it forms part of the border between the two countries. It flows into the Marecchia at Torello, part of the commune of San Leo (Province of Rimini).