Mallorca runs scheduled passenger boats to the three places people most often try to reach from Palma. None of them leaves from Palma, and that is the whole cost of the saving.
Cabrera. The archipelago south of Mallorca is a maritime-terrestrial national park, and you cannot simply sail there. Access is by an authorised passenger operator or with a prior navigation and mooring permit; the park is capped at 300 visitors a day and, since the courts upheld the limits, at 80 people per boat. The licensed companies — Excursions a Cabrera, Cabrera Sea Fun, Ona i Mar and Aventura Ibsub among them — must apply for their authorisation between the first of January and the end of February each year, and they all sail from Colònia de Sant Jordi, an hour's drive southeast of Palma. Entry to the park is free; the boat is the ticket, at roughly €45–56 for a three-hour trip and €58–71 for the full day, with the crossing taking 40 minutes to an hour depending on the hull. No boat on this page goes there.
Sa Calobra and the Torrent de Pareis. Barcos Azules sail from Port de Sóller on the northwest coast — reachable from Palma on the vintage Ferrocarril de Sóller — with an adult return to Sa Calobra at €35, about an hour each way, departures at 09:50, 11:20, 13:00 and 15:00 daily between the first of April and the end of October, and returns at 13:40 and 16:45. Cala Tuent is the same fare. That is the most spectacular hour of coastline in the Balearics and it costs less than half of any guided catamaran day — but it is a two-hour round trip from Palma before you board.
Formentor. The ferry from Port de Pollença to Formentor beach takes about 25 minutes and runs around €18–20 return, with returns at 11:30, 12:30, 13:30, 15:30 and 16:30 and a 18:00 sailing added in July and August. It is a shuttle, not an excursion: no guide, no swim stop, no drink.
The honest sum. Two adults on the cheapest Palma bay boat, the $38 s'Arenal trip, cost about the same as two Sa Calobra returns. What the €70 of scheduled ferry does not buy: a skipper who moves the anchorage when the embat gets up, snorkelling gear over the side, shade and a toilet on a five-hour day, or the caves at Portals Vells, which no scheduled boat visits. If you want to stand somewhere, take the ferry. If you want the day on the water, the catamarans are what you are actually buying.
The same test applies to the Coves del Drach excursion. It is a coach trip, not a sailing: the boat part is a rowing boat on the Martel lake after the classical concert. Entry to the caves has been listed at €18 for adults and €11 for children aged two to twelve on the caves' own tariff, so the coach, the guide and the seat account for the rest of the $63. Driving yourself to Porto Cristo makes it far cheaper and costs you a day of parking.