Update August 2017: In addition to the options presented below, there is now a direct flight operating between Malaga and Tangier by the airline Air Arabia Maroc four times per week. Iberia has also launched a direct flight on this route. Flying may be cheaper and more convenient than taking the ferry.
There are many ferry operators ready to take you the short journey from Europe to Africa. Morocco is actually visible from many parts of Spain’s southern coast. Most companies have modern and high-speed ferries, with the shortest connection between Spain and Morocco taking just 30 minutes.
However, it tends to take much longer, since these ferries are not known for their punctuality. If you are in a rush or need to be somewhere urgently, it would be recommendable to take an earlier ferry, since the crossing times published by the ferry companies are often useless. The immigration and customs checks on both the Spanish side and the Moroccan side are also quite inefficient, and can take a lot of time depending on the time of the year you are travelling, so bear in mind that you may get held up for a while.