Passage 3.22.3
ἐν ἀριστερᾷ δὲ Γυθίου στάδια προελθόντι ὡς τριάκοντα ἔστιν ἐν τῇ ἠπείρῳ Τρινασοῦ καλουμένης τείχη, φρουρίου ποτὲ ἐμοὶ δοκεῖν καὶ οὐ πόλεως. γενέσθαι δέ οἱ δοκῶ τὸ ὄνομα ἀπὸ τῶν νησίδων, αἳ ταύτῃ πρόκεινται τῆς ἠπείρου τρεῖς ἀριθμόν. προελθόντι δὲ ἀπὸ Τρινασοῦ στάδια ὡς ὀγδοήκοντα τοῦ Ἕλους τὰ ἐρείπια ὑπόλοιπα ἦν, καὶ μετὰ ταῦτα τριάκοντα
On the left, about thirty stades beyond Gythium, upon the mainland, there exist walls of a site called Trinasus, which I believe were once those of a fortress rather than a city. I think it gets this name from the three small islands situated offshore at that place. About eighty stades from Trinasus were the surviving ruins of Helos, and thirty stades further along after these ruins...