Palma Aquarium opened in 2007 and sits on the coastal road between S'Arenal and the airport, about 10 minutes by bus from the resort. It is the most substantial indoor attraction on this part of the coast, with over 700 species of marine life displayed in tanks representing ecosystems from the Mediterranean to the open ocean.
The highlight is the large shark tank with its glass tunnel walk-through, though the Mediterranean section — showing the ecosystems directly under the Bay of Palma — is more informative for anyone curious about what is actually out there when they swim. There is a good children's section and a restaurant. Entry is around €25 for adults in high season; the aquarium is open year-round, making it a useful option on a rainy day.