Capri is reached by hydrofoil or ferry from Naples (Marina Molo Beverello), Sorrento, Positano, Amalfi, and Salerno. From Naples the fast hydrofoil takes about 45 minutes; the slower ferry takes 80 minutes. From Sorrento the crossing is 20 minutes. Hydrofoils and ferries run frequently in summer (roughly every 30 to 60 minutes from Naples); services thin out considerably in winter.
The main ferry lines are Caremar, SNAV, NLG, and Alilauro. All arrive at Marina Grande on the north side of the island. Tickets can be bought at the port on the day; no reservation is generally needed except in peak summer. The last return hydrofoil to Naples typically leaves around 8pm — check current timetables before making an evening reservation on the island.
There is no way to bring a private car to Capri; the island does not permit them for non-residents. Buses, taxis, and a small funicular are the only motorised options once you arrive.