The two best wild beaches on Samos sit on the north-west coast and can be reached only by walking (or by sea-kayak in calm weather). The path starts above the hamlet of Potami and contours the cliffs for about an hour to Mikro Seitani, a tiny pebble cove with no facilities, then continues for another forty minutes to the bigger sand-and-pebble Megalo Seitani.
Bring everything you need — there is nothing on either beach. Both fall within a protected area where the Mediterranean monk seal still occasionally raises pups; you may see seal traces in the sand but you will probably not see a seal. The walk is exposed; do it early in the morning in summer.