The longest flowing rivers in Greece are the Evros and the Axios Rivers. However, both originate from adjacent countries outside Greek territory; the Evros in Bulgaria and the Axios in the Republic of North Macedonia, while the length of the Greek river section is limited). The longest river that originates in the country is the Aliakmon River, which flows through Western Macedonia and empties into the Thermaikos Gulf.
Important ecosystems and hydro-biotopes have formed along the lengths of many rivers, as well as at their estuaries. Many of these are especially well-known and are protected by international agreements.
During the summer months, cultural events are held by many riverside communities, while the visitor can also take part in water sports in many rivers.