Morfa Harlech National Nature Reserve is a nature reserve in Wales, located north of Harlech.
It reaches across expanses of open sand and sea towards Snowdonia. One of two extensive sand dune systems which make up much of the sandy Meirionnydd coastline, it carries particular importance as the only growing dune system in Wales.
Nearby is Harlech Castle, which due to the expanding dune system has been taken back 1,000 metres (3,300 ft) from its original position on the coastline 600 years ago.