The Longest Sinking Rivers In The World

The Trebisnjica River near Lastva, Bosnia and Herzegovina.
The Trebisnjica River near Lastva, Bosnia and Herzegovina.

What Is a Sinking River?

Sinking rivers are a major feature of karst landscapes. Sinking rivers are seen to disappear into the ground in the course of the flow thereby recharging the local groundwater and may reappear further downstream. Sinking rivers, also referred to as losing streams or influent streams, decrease in volume as opposed to the gaining steam or effluent stream which increases in water volume as it flows downstream. In regions with karst topography, river or stream water may completely disappear into the underground cavern system thus becoming a subterranean river.

The Longest Sinking Rivers In The World

The Trebisnjica

The Trebisnjica has a unique phenomenon and is the longest sinking river in the world. The Trebisnjica River, which was formally known as Arion, has a total length of 116.2 miles and consists of many above and underground watercourses. The river originates from the southeastern region of Bosnia and Herzegovina where two streams are running from Mount Cemerno and Mount Lebrsnik flow through three karst field namely Gatacko, Fatnicko Polje, and Cernicko. The water flows 31 miles underground before emerging as multiple springs near the town of Bileca where they form river Trebisnjica. Trebisnjica, which is also the largest underground river, then flows 60.9 miles through the Popovo Polje karst fields and reemerges as three outflows. Two of the outflows emerge as springs, one as the Capljina spring and the other as a warm spring near the town of Slano in Croatia. The third outflow moves 12.4 miles underground before reemerging as the Ombia River near the Gruz cave.

The Unac River

The Unac River is a sinking river in Bosnia and Herzegovina. The river rises from the Sator Mountain and is one of the main tributaries of the Una River. River Una then flows 131.7 miles into the river Sava. The River flows through the municipality of Drvar and also runs through two deep Krastic canyons. The river Unac is dammed to form Lake Prekajsko and Lake Zupica near the town of Drvar. The River measures 40.7 miles and is a popular tourist attraction due to its clean and clear waters fishing as well as rafting due to the abundance in rapids.

The Reka

The Reka is a river located in Croatia and flows through western Slovenia. The river has an estimated length of 34 miles with 24 miles of it flowing underneath the karst in Slovenia.

The Suica

The Suica measures 30.1 miles and is located in Bosnia and Herzegovina. The river flows through Duvanjsko and Tropolje and begins its subterranean section at Kovaci where it goes underground. The Suica then emerges at the source of Ricina in Prisoje before emptying into Busko Blato reservoir.

The Sinking Creek

Sinking Creek River is located in the state of Virginia in the United States and measures 19.8 miles in length. Sinking Creek sinks due to the karst topography in the Scott and Russell counties. The Sinking Creek is a wonder to behold as it crosses River Clinch underground before emerging on the northern side of river Clinch.

Sinking River Resources

Sinking rivers represent great potential that has not been sufficiently exploited. The rivers form unique tourist attractions and are ideal for sporting activities such as diving, fishing, and kayaking.


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