Ibiza Airport: For Ibiza Town, take airport bus L10: roughly 20–25 minutes, €3.60 cash (the evidence says cash only; frequency is about every 15–20 minutes in summer, less often in winter). For Sant Antoni, use seasonal L9 direct (about hourly in June–September; €4); out of season, take L10 into Ibiza Town and change to L3 or L8. For Santa Eulària, Es Canar and Cala Nova, seasonal L24 is the sensible direct option, about hourly and €4. If you need a taxi, use the official rank outside the terminal—not a pre-booked fixed-price tout; licensed-rank taxis are reported to be markedly cheaper.
Port of Ibiza Town (ferries from Formentera, Mallorca and mainland Spain): If staying in Ibiza Town, walk from the port to La Marina/Dalt Vila or take a short licensed taxi with luggage. For onward resorts, use Ibiza Town as the bus hub; it is the practical place to change rather than paying for an island-crossing taxi. There is no railway on Ibiza.