The waters around the island are fairly shallow and there are several lovely beaches: Molos, Sifnaikos, Diopori and Soros. The sand is fine and golden. The west coast is slightly less explored than the east, if you're looking for solitude on the beach. The surrounding islets are good fishing areas as well.
The famous Antiparos Cave is on the west side of the island in the hill of Aghios Ioannis. It's rich with stalagmites and stalactites.
The tiny chapel of St. John Spiliotis (1774) is at the caves entrance. The enormous stalagmite known as the 'alter table' is so named because on Christmas day 1673 the French Ambassador de Nointle celebrated midnight mass there, as we are told by the commemorative inscription in Latin at its base. The story is that five hundred Greek Orthodox parishoners were paid to attend the Catholic service.
Many famous souls have left traces of their visits on the stalagmites and stallactities including Lord Byron and King Otho. Many seeking to escape Alexander the Great hid in the cave and left markings. Many inscriptions were taken by Russians officers when in 1774 they chopped them off as souveniers. Many more were lost during WWII when Nazi and Italian troops shot up the cave. The cave is protected from such destruction now.
Buses or boats take visitors to the cave which is open 10:45 AM to 3 PM (fee charged). From the cave mouth it is a dramatic 210 descent feet in to the remakable cavern. The cave is really much deeper, but dangerous, and its lower recesses are closed to the public.