John Fowles wrote a novel in the ’60s called The Magus which brought a splash of attention to the area since Spetses is mentioned in the pages of his book. Now, thanks to the movie, it’s possible that more travelers will be headed in this direction.
Sceenit mentions the fact that Spetses is considered a historic zone that belongs to an island group of individuals called the Argo-Saronics. You’ll find Spetses at the opening of Argolic Bay with nearly 4,000 permanent residents living there.
Source: https://www.distractify.com/p/where-was-glass-onion-filmed