The Šventoji (; The Holy One) is the longest river that flows entirely within Lithuania and the largest tributary of the Neris. It originates from Lake Samanis in the Gražutė Regional Park and flows into the Neris near Jonava. In 1959, the Antalieptė Reservoir, the second largest artificial lake in Lithuania, was built on the Šventoji.
Tributaries
The following rivers are tributaries to the river Šventoji (from source to mouth):
- Left: Šavaša, Vyžuona, Aknysta, Taurožė, Beržuona, Elmė, Anykšta, Virinta, Dagia, Širvinta
- Right: Kriauna, Nasvė, Jara, Pelyša, Vadaksta, Grieža, Latava, Biebė