Going to Formentera is easy. You will just need to take the ferry from Denia, Barcleona, Alicante, Palma or Barcelona. There are regular crossings during the high season (May to September), but outside on this season your options are a lot more limited and you will almost certainly need to enter the island at the port of La Savina on a boat that has come from Ibiza. The crossing to Formentera from Ibiza should only take 30 minutes, but the channel of Es Freus does have some strong currents which can slow you down on a choppy seas.
Once you arrive at the port of La Savina, you will step off the boat to face the Tourist Information Office. This is a great first stop to pick up leaflets and maps, and chat to the staff about the best things to do. A nice lady named Carmen is usually at the office and more than happy to give practical advice and insider tips. What you decide to do will very much depend on how long you are planning to stay on the island. If it is just a day trip then you should exit La Savina and head to Es Trucadors.
Es Trucadors is an amazing stretch of white sand beaches, coves, islets, turquoise waters, views out to Es Vedra and S’Espalmador, and rampant naturism. If you are offended by naked bodies soaking up rays of sunshine then this may not be the place for you after all. However, if that is not a problem then you can cycle there in twenty minutes from La Savina and enjoy the views. Of all kinds.