How do you retire a 5-ton whale? That’s a question some advocates and scientists have been asking themselves in the wake of SeaWorld’s historic decision in March to stop breeding the 29 orcas in its care. Now, a new organization of about three dozen scientists, marine veterinarians, and engineers called the Whale Sanctuary Project has begun developing plans for an orca sanctuary, including coves and small groups of islands that could be cordoned off. Other groups have proposed similar plans. But critics say that placing an orca that has spent its entire life in a sterile, concrete tank into an ocean filled with creatures and conditions it has never encountered before could be dangerous not just for the whale but for the previously whale-free ecosystem. Plus, the costs are mammoth—perhaps tens or hundreds of millions of dollars. So who’s right? And how will the next steps impact the fate of SeaWorld’s orcas, plus another 27 killer whales in theme parks and aquariums around the world? For the full story, check out this week’s feature in Science.