Ischia and Procida
From IL NIDO you can reach the port in Sorrento with the free minibus service. Hydrofoil to Ischia run less frequent than to Capri ....but is also possible to get there. For Procida you've to reach Napoli first. What I suggest is a splendid minicruise in the Gulf of Naples organized by MARIN CLUB, a beautiful ship that leave everyday from the Port of Sorrento.
ISCHIA:
It is the largest of the island in the bay of Naples, the "green island" for its abundance of pine-tree forest. Its vulcanic nature makes it unique in the orld for the great variety of thermal and radioactive springs, pratically found every where on its territory.
PROCIDA
It is the smallest of the three islands of the bay of Naples, and surely the most genuine. It is the island where it is still possible to admire the typical classical architecture 0f Mediterranean pink and white washed houses inhabited by the fishermen still living on the island.
From the Port of Sorrento is possible to reach only Ischia. For Procida, Naples must be reach first.
Ischia is divided into six commune districts and Ischia is the major tourist port for its importance; The "Ponte" area is distinguished by the rock on whic the Aragonese Castle was built.
Procida is almost totally flat and on the only headland lies a tufa building used as a penitentiary in the past.
You can visit both Islands with a great Minicruise with the ship "Marine Club" that leave directly by the Port in Sorrento. Tickets are selled at the Port or in the Main Travel Agency