Tol Morwen was one of the three islands off the coast of Lindon. It was a remnant of the drowning of Beleriand, and on it stood the memorial stone of Túrin Turambar, Nienor, and Morwen.
Location
The place is only attested in the texts, and neither the grave of Morwen nor the later island are represented on any of Tolkien's maps published so far. Being close to the gorge of Cabed-en-Aras, the location of this site may nevertheless reasonably be inferred near the gorges of the Teiglin and above its ravines.
Superimposing the map of Beleriand in the First Age and the map of the Westlands in the Third Age therefore allows to approximate the location of the island.
During the drowning of Beleriand at the end of the First Age, the site of the Stone of the Hapless did not drown but, as predicted by Glirhuin, remained as an island, Tol Morwen, which was the grave of Morwen Eledhwen, hence its name. It was the westernmost of the islands in Belegaer located off the coast of Forlindon.