Zogeria
If you are visiting the island with a sailing yacht or catamaran, then Zogeria is one of the best beaches to anchor. Surrounded by a pine forest, dressed in a sandy outfit and filled with sapphire waters surely will dazzle you with her presence. Zogeria is also a nice spot if you would like to overnight onboard, as the water is smooth and the weather is calm most of the times as well. There is a small chapel and a small tavern available.
Spetses is for me the most beautiful island of the Saronic overall. She has the most beautiful atmosphere, colors, aromas and above all places to drom an anchor and relax with a great scenery! If you are planning to stay in the harbor then you should enter the port quite early since most of the times its packed. Try the old port, since the new is not friendly for sailing yachts or catamarans due to the swell and the high speed passenger ships that touch and go, creating waves that are quite annoying
-Eugene suggests