Have a car and want to bring it to the island? It is possible from the South of mainland Spain with huge commercial ferries that can transport cars and passengers. There are about 3 departure weekly total. Pick the date that works best for you then depending on that you´ll leave from either Cadiz or La Huelva. Note that Cadiz is worth visiting; La Huelva, not so much.
The trip is over 30 hours, the exact amount depends of the city you depart from. With Armas, we highly recommend that you book a cabin, it is totally worth it, as you will be much more comfortable than just in a normal seat. Cabins have beds, plugs, wifi, personal hot shower & toilet, and optionally a window to the sea. And cherry on top. all cabin reservations include all the meals during the journey. The ferry has a nice deck with a pool and a bar, so enjoy it like a cruise!