The summer months are the busiest, of course, but also when you'll find most of the cafés and bike/moped/scuba gear rental shops in operation.
Getting there
Planes
Touch down at Ibiza Airport, the main point of arrival for the islands. From there, hop on a ferry to Formentera. There are year-round flights from London Heathrow and City airports, Paris-Charles de Gaulle and major Spanish cities, and seasonal services from almost every European destination you can name.
Boats
Ferries leave Ibiza from various spots: the main port is in Ibiza Town, and boats leave every half hour in high season. You don’t technically need to book your place in advance, but at busier times of year it might save you a wait (especially if you’re in a car).
Automobiles
If you decide to rent a car, you'll have greater choice in Ibiza. Pick up your ride in Ibiza and drive right on to the ferry.