The Ausa River is a river of northern San Marino

San Marino

San Marino, officially the Republic of San Marino , is a state situated on the Italian Peninsula on the eastern side of the Apennine Mountains. It is an enclave surrounded by Italy. Its size is just over with an estimated population of over 30,000. Its capital is the City of San Marino...

 and Emilia–Romagna in Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

. The source of the river is Monte Titano

Monte Titano

Monte Titano is a mountain of the Apennines and the highest peak in San Marino. It stands at above sea level and is located immediately to the east of the capital, San Marino. It was inscribed as a UNESCO World Heritage Site in 2008 under the combined title "San Marino Historic Centre and Mount...

 in central San Marino. The river flows northeast past Serravalle

Serravalle, San Marino

Serravalle is a castello located in the European republic of San Marino. With a population of 9,394 inhabitants and a surface of 10.53 km², it is not only the most densely populated municipality in San Marino, but it also contains its largest city...

 and crosses the border into the Italian province of Rimini

Province of Rimini

The Province of Rimini is a province in the Emilia-Romagna region of Italy. Its capital is the city of Rimini. It borders the state of San Marino.-History:...

 close to Dogana

Dogana

Dogana may be:*Dogana, a town of San Marino*Dogana, means customs in Italian and can refer to :** Individual Custom Houses such as that of Venice**Agenzia delle Dogane , the Italian customs organisation...

. The river continues flowing northeast and runs through Rimini

Rimini

Rimini is a medium-sized city of 142,579 inhabitants in the Emilia-Romagna region of Italy, and capital city of the Province of Rimini. It is located on the Adriatic Sea, on the coast between the rivers Marecchia and Ausa...

 before emptying into the Adriatic Sea

Adriatic Sea

The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges...

 south of the mouth of the Marecchia

Marecchia

The Marecchia is a river in eastern Italy. In ancient times it was known as the Ariminus which was from the Greek Ariminos, Αριμινος . The source of the river is east of Pieve Santo Stefano and southwest of Badia Tedalda in the province of Arezzo in Tuscany...

River. At 55 m above sea level, it is the lowest point of San Marino.