Matapan & Maleas, Capes
Capes Matapan (Tainaron) and Maleas in the Peloponnese are the two most southerly points of mainland Greece. They have been proposed by Galanopoulos & Bacon  as the Pillars of Heracles, when the early Greeks were initially confined to the Aegean Sea and the two promontories were the western limits of their maritime knowledge.>They note that
“This has been the subject of some interesting conjectures. Nearly all the labours of Hercules were performed in the Peloponnese. The last and hardest of those which Eurytheus imposed on the hero was to descend to Hades and bring back its three-headed dog guardian, Cerberus. According to the most general version Hercules entered Hades through the abyss at Cape Taenarun (the modern Cape Matapan), the Western cape of the Gulf of Laconia. The Eastern cape of this gulf is Cape Maleas, a dangerous promontory, notorious for its rough seas.
Pausanias records that on either side of this windswept promontory were temples, that on the west dedicated to Poseidon, that on the east to Apollo. It is perhaps therefore not extravagant to suggest that the Pillars of Hercules referred to are the promontories of Taenarum and Maleas; and it is perhaps significant that the twin brother of Atlas was allotted the extremity of Atlantis closest to the Pillars of Hercules. The relevant passage in the Critias (114A-B) states:
‘And the name of his younger twin-brother, who had for his portion the extremity of the island near the pillars of Hercules up to the part of the country now called Gadeira after the name of that region, was Eumelus in Greek, but in the native tongue Gadeirus — which fact may have given its title to the country.’
Since the region had been named after the second son of Poseidon, whose Greek name was Eumelus, its Greek title must likewise have been Eumelus, a name which brings to mind the most westerly of the Cyclades, Melos, which is in fact not far from the notorious Cape Maleas. The name Eumelus was in use in the Cyclades; and the ancient inscription (‘Eumelus an excellent danger’) was found on a rock on the island of Thera.
In general, it can be argued from a number of points in Plato’s narrative that placing ‘the Pillars of Hercules’ at the south of the Peloponnese makes sense, while identifying them with the Straits of Gilbraltar does not[p.97].”<