The Siret or Sireth (, ; or ; ) is a river that rises from the Carpathians in the Northern Bukovina region of Ukraine, and flows southward into Romania before it joins the Danube. It is long, of which a section is in Romania, and its basin area is ,
The river initially flows northward in the region of Northern Bukovina. The section of the river up to its confluence with the Siretul Mic (Malyi Seret) (near Suceveni (Sucheveny) village in the Adâncata district (Hlyboka Raion)) is called the Siretul Mare. The river is called Siret after its confluence with the Siretul Mic.
The river flows through the towns of Berhomet on the Siret and Jadova, where it begins to change its direction of flow to the southeast. It continues its flow through the town of Storojineț and the villages of Ropcea, Camenca, Volcineț, and Cerepcăuți.
The Siret leaves Ukrainian territory and enters Romania in the north-east. Initially forming the border between Suceava and Botoșani counties, it continues in a southeastern direction. It passes through Siret, the former capital of Moldavia (in the second half of the 14th century), and then through Grămești, Zvoriștea, and Liteni. The 170 km-long Suceava River flows into the Siret on the right near Liteni, around from Suceava. Later that day, the Siret river threatened to break through the dykes protecting the town of Șendreni, as locals and emergency services reinforced the dykes with truckloads of sandbags to prevent the river breaking out and flooding the town.