Naples International Airport / Capodichino: There is no airport rail link yet. Take the €5 Alibus to Napoli Centrale/Piazza Garibaldi, then Metro Line 2 to Piazza Amedeo for Chiaia: allow 45–60 minutes total and roughly €6–7. It is slower than a taxi but avoids the airport-taxi theatre. Late at night, use only the official rank; ask for the applicable fixed fare or insist on the meter before the car moves.
Napoli Centrale / Piazza Garibaldi: For Chiaia, use Metro Line 2 from Piazza Garibaldi to Piazza Amedeo—about 10–15 minutes, then a short walk downhill or across the quarter. A city ticket is roughly €1.50–2. Do not confuse the sprawling Centrale, Garibaldi, Circumvesuviana and Line 1 sections: allow 10 minutes just to find the right entrance/platform.
Napoli Afragola high-speed station: Afragola is useful only if your train stops there; it is 12 km north of central Naples and not Chiaia. Take the next rail connection/shuttle toward Napoli Centrale, then Line 2 to Piazza Amedeo. Budget at least 45–75 minutes after arriving at Afragola, depending on the connection; do not accept it as equivalent to Centrale when choosing a ticket.
Napoli Mergellina station: A handy but less universal arrival point for trains that call there. Chiaia’s western end and the Mergellina waterfront are walkable in about 10–20 minutes; Piazza Amedeo and the shopping core are farther east. It is much more convenient than Centrale if your accommodation is near Via Caracciolo or Mergellina.
Molo Beverello / Stazione Marittima ferry terminal: For Capri, Ischia and Procida ferries, this is the practical Naples port. Chiaia is 25–35 minutes on foot along/behind the waterfront, or a short licensed-taxi ride with luggage; do not plan on a seamless direct metro connection to the docks.