Stiniva is the most famous beach on Vis and the single image that ends up on every guide to the island. The cove is roughly circular, walled by 70-metre cliffs, and reached either by boat (most visitors) or by a steep half-hour hike down from the rim road on the southern coast. The water is the standard Adriatic glass-clear; the beach itself is fist-sized pebbles, painful to walk on, blessed for swimming away from.
It is small — perhaps thirty metres across at its widest — and packed by midday in July and August. Go early, bring water and shoes, and consider continuing along the southern coast to the smaller and emptier Srebrna or Zaglav beaches.