Virgin Holidays have stopped selling tickets to shows where marine animals are kept captive.
The firm announced that its ended partnerships with five such venues including SeaWorld and Discovery Cove.
Virgin founder Richard Branson said they would now only "work with suppliers that don't take sea cetaceans from the wild".
Amusement parks like SeaWorld have been criticised for their treatment of dolphins and killer whales.
SeaWorld have responded to the decision by saying that activists "mislead and manipulate marine mammal science to advance their agendas".
In a statement, they said "no company does more to protect marine mammals and advance cetacean research, rescue and conservation."

DIFC registers over 10,000 active companies for first time
DEWA International explores partnerships with several Greek companies
UAE to get 100 Primary Care facilities by 2030
DEWA discusses expanding international operations in UK
Australia plans first domestic oil refinery in 60 years to boost fuel security
