Nahal Ayun Nature Reserve, Nature reserve in Galilee Panhandle, Israel.

Nahal Ayun Nature Reserve protects a section of Nahal Ayun near Metula, on Israel's border with Lebanon. The stream runs through a deep channel cut by four waterfalls: Ayun (9.2 m), the Mill waterfall (21 m, named for a flour mill whose remains lie at its foot), Ashd (9.5 m, followed by a further split fall of about 5 m), and Tanur (about 30 m). The reserve was declared on 13 June 1968 over roughly 405 dunams and designed by architect Zvi Dekel.

In 1929 Metula resident Franz van der Horst founded the "Association for the Waterfall", whose members cut trails and planted poplars to open the reserve to walkers. A 1963 committee proposed a 100-dunam reserve with the Tanur and Mill falls; the access path between the upper fall and Tanur was begun in late 1964. The reserve was declared on 13 June 1968 over about 405 dunams, planned by architect Zvi Dekel.

The reserve is named after the biblical city of Iyon. A mill once stood at the foot of the 21-metre Mill Waterfall, and only its remains survive; the waterfall still carries its name. Near that fall, the Ein Sukhra spring fed a dam and pump that supplied Metula's drinking water until 1957.

Two marked trails guide visitors through the reserve: a longer descent visiting all waterfalls or a shorter walk to the main cascade. After rain the water flows much stronger, and sturdy footwear is essential since rocks and soil paths can be slippery when wet.

The reserve is named after the biblical city of Iyyon, and the spring of Ein Sukhra beside the Mill Waterfall once fed a dam and pump that supplied Metula's drinking water until 1957. About 900 mm of rain falls on the stream and its surroundings each year.