More than 200 bottle-nose dolphins have been captured from around the Solomon Islands.
Campaigners say this is an "environmental crime".
Tricks
It's thought theme park bosses are paying up to £100,000 per dolphin.
But animal rights activists say it's cruel to take dolphins from their natural habitat and make them do tricks.
Coffin-like containers
The animal activists, and the Australian Government, are calling for the trade to be stopped.
But Mexico says it has the proper permits and no law's being broken, so there's no need to stop.