Dduallt (English: Black hill) (pronounced [ðɨ.æɬt]) is a mountain in central Snowdonia, north Wales.

It lies north of the A494 between Dolgellau and Llanuwchllyn.

Its eastern slopes are the source of the Afon Dyfrdwy (River Dee).

[1] It is normally climbed from the SW (often with Rhobell Fawr) as there are large boggy areas to the N and E and very steep E face.

This Gwynedd location article is a stub.