Mynydd Marchywel
The larger part of the hill is cloaked in modern forestry through which numerous streams fall away westward to the River Tawe , eastward to the River Dulais and southward into the Clydach , the latter two being tributaries of the River Neath . 
<triplet> River Dulais <subj> River Neath <obj> mouth of the watercourse <triplet> Clydach <subj> River Neath <obj> mouth of the watercourse <triplet> River Neath <subj> Clydach <obj> tributary