What is the best beach in Milos?

Sarakiniko is the answer, and it's not particularly close. The volcanic rock formations give it a surface that looks genuinely lunar, brilliant white pumice carved into smooth curves by wind and sea, with deep blue water cutting through the channels between the formations. There's nowhere else quite like it in Greece, and arguably nowhere quite like it on earth. It costs nothing to reach, there's no resort infrastructure demanding your money, and the light at midday or late afternoon is something photographers would plan entire trips around. Go early or go at golden hour if you want it to yourself.

From Sarakiniko, the logical move is to work east along the north coast toward the old sulfur mines at Paliorema, which rewards anyone willing to explore a bit beyond the headline beach. The island generally runs on that kind of rhythm, unhurried, unselfconscious, and remarkably free of the choreographed beach experience that Mykonos has turned into an art form. You get a chair without a reservation and a view without negotiating around someone's Instagram setup. That alone is worth something.

I've stayed at Phos Milos up in Pollonia, which puts you on the quieter northeast end of the island and makes Sarakiniko a straightforward day trip rather than a production. That part of the island has a different, more local feel than the area around Adamas, and it's worth considering if you want the beach without the busier town energy.