The dolphin show is sold as a full day excursion during week days. It can also be combined with Palma sightseeing, Western Water park, Katmandu or a boat trip. Journey time is approximately one hour.
You can find full info on their website https://www.marineland.es/mallorca/en/
The nearest thing to swimming with the dolphins is this: https://www.marineland.es/mallorca/en/educacion-2/
Excursions including Marineland:
Marineland all Day
Adult 44,50€ / Child 29€ - pick up 8:45
Marineland + Katmandu House
Adult 70€ / Child 40€ - pick up 8:45