Formentera has no airport. The only way in is by sea, and the only regular route is the ferry from Ibiza. The crossing takes between 25 minutes (fast ferry) and 55 minutes (slower car ferry) and runs frequently throughout the day in summer, with a reduced schedule in the shoulder season and winter. Several companies operate the route, including Balearia and Trasmapi; buy tickets in advance during July and August, when the fast ferries sell out. The ferry terminal in Ibiza is at the southern end of the harbour, a short walk from the old town. On the Formentera side, all ferries arrive at La Savina.
There are also seasonal high-speed connections directly from the mainland — Denia on the Valencia coast has summer ferry services to both Ibiza and Formentera. Coming from Barcelona or Valencia, this can be an attractive option if you want to avoid Ibiza entirely. Travelling with a car adds complexity and significant cost; for a short stay the island is small enough that a bicycle or scooter is genuinely sufficient.