The distance between the capital of Spain's Catalonia region, Barcelona, and Palma de Mallorca (Palma), the capital of Mallorca (i.e. the largest of the Balearic Islands) is 128 miles (206 km). Hands-down the quickest and most logical way to make the trip is by direct flight, which takes less than one hour.
Another viable option is to take a car ferry. Direct ferries from Barcelona to Palma will take about 7.5 hours. You can also take a ferry to Alcúdia (6 hours) on the other side of the island, which is only 35 miles from Palma.
For a luxurious travel experience, private helicopter charters are also available. The trip takes about an hour.
Before you go, make sure to check out kimkim's Highlights of Mallorca: Beaches, Mountains, and Culture.
Duration: 1 hour (flight time)
Hands down the most logical, efficient, and affordable option is to fly from Barcelona's airport El Prat (BCN) nonstop to Palma de Mallorca Airport (PMI). Vueling Airlines, Ryan Air, Iberia, Air Europa and British Airways all run many direct flights daily at a competitive cost, especially if tickets are booked in advance.
Keep in mind that El Prat airport is located about 10 miles from Barcelona's city center, and heavy traffic is common. PMI airport is just fifteen minutes by taxi to the Palma.
Duration: 7.5 hours
Barcelona is a port city on the Mediterranean, meaning that the sea is a great means of travel to the Balearic islands. Two companies offer daily car ferries: Trasmediterránea and Balearia, and both take about 7.5 hours.
Trasmediterránea offers two direct routes a day, Although schedules change seasonally, note that trips may be overnight and cabin accommodations can be more expensive than seats. Bringing your car will also cost more than walking on, but will give you the added perk of having a car on Mallorca.
Barcelona's port is huge, and you should figure out how to get to each ferry in advance. Balearia leaves Barcelona from Terminal Port Nou. Trasmediterránea departs from Muelle de San Beltrán near Plaza Colón. Both companies come into the Puerto de Palma de Mallorca which is a much more manageable port.
Balearia only offers one direct ferry daily, but also runs one direct ferry to Alcúdia, which is on the opposite side of the island of Mallorca. This ferry takes only 6 hours, but once in Alcúdia you will need to coordinate a transfer. Driving from Alcúdia to Palma takes about 45 minutes. Also note that the Alcúdia leaves Barcelona from a different dock, located at Drassanes (Moll Barcelona).
By Private Helicopter
Duration: ~1 hour
If there is any occasion to charter your own private helicopter, swooping over the Mediterranean is surely a great reason. Multiple private helicopter companies offer trips that also include ground transport in Barcelona and Palma. Trips can be tailored to corporate or luxury travel groups, and often include catering options. Some helicopter companies also offer planned sightseeing tours in the Balearic Islands.
For more information on travel in the islands and coastal cities of Spain, make sure to read kimkim's guide to Spain in July.