Belnahua (Beul na h-Uamha) meaning 'the mouth of the cave' is one of the Slate Islands in the Firth of Lorn, Scotland.
Known for its slate quarries Belnahua lies 1.5 miles (2.4 km) north west of Luing west of Argyll, and east of the Garvellachs. Although it once had a population of nearly 200 people, it has been uninhabited since World War I. Famed for its slate, the island has been considerably denuded by its quarrying. Deep water-filled cuttings and the ruined slate workers cottages remain as a testament of this industry.
There is a jetty to the east and an extensive drying reef to the north west. The Latvian vessel Helena Faulbaums foundered on the reef in 1936, with the loss of 16 lives.
A quiet home for local wildlife, the island is occasionally a stop off for local fisher folk and tourists. It is currently owned by the Carling family.
OS grid reference: NM713127