Ferries to the Balearic Islands (Mallorca, Ibiza, etc.)
Every day a large number of ferries operate between the Spanish mainland and the islands of Mallorca and Ibiza, and more rarely to Menorca and Formentera. The main ferry ports on the mainland are Barcelona and Valencia. There are also some ferries from Denia and Alicante (both on the Costa Blanca).
The slow ferries are cheaper than the fast ships. Normal ferry services to Mallorca or Ibiza are often at night and typically take 6-10 hours. The fast ferries (catamarans, super ferries and other names) need only 3-4 hours, but are about 50% more expensive. There are different companies, which differ in price: Trasmediterranea, Balearia and Iscomar are big companies on this route. A one-way trip often costs around 50 euros, for the fast ferries 70-80 euros. However, there are many offers and discounts, almost like in air travel. Cars can be taken on all ferries. But this costs some extra. Often return tickets are cheaper than simple tickets. Some tickets can be rebooked, do not. Finding the best offer is not always easy.
There are also ships between the Balearic Islands. These ferry connections are often expensive, especially if there is no competition.
Ferries to Morocco
Here, too, finding the best offer is not always easy. There is even more competition and a confusing number of offers. There are many ports of departure in Spain: Algeciras, Almeria, Gibraltar, Malaga and Tarifa. In Morocco the most important ports are Tangier and Ceuta (city belonging to Spain), but there are also others. Algeciras to Ceuta is with about 40 minutes driving time probably the shortest connection.
Ferries to the Canary Islands
The Canary Islands are more than 1000 kilometres away from the Spanish mainland. By ferry this means at least 2 nights and one day travel time. The ferry is accordingly rare (only once a week) and accordingly expensive (over 200 euros per person for a single trip). There is a cabin obligation and all tickets were for my crossing 2006 including full board. The ship of the company Trasmediterranea departs from Cádiz in southern Spain. It departs from Gran Canaria, Tenerife and La Palma and then goes back to Cádiz (on the way back also stop in Lanzarote). This tour lasts one week. Many passengers travel with this ferry to transfer their vehicle or due to fear of flying. A cheap flight is cheaper than the ferry crossing to the Canary Island.
Ferries to Italy
A really useful ferry connection runs from Barcelona over the Mediterranean Sea to Civitavecchia near Rome (Italy). The ferry runs daily and is very cheap. There are also other ferries from Barcelona to Italy (Livorno and Genoa). To my knowledge there are currently no ferries from France or Italy to Mallorca. Cheap airlines have caused the suspension of many ferry connections in Europe.