Western Australian wildlife officials are hunting for a dolphin seen wrapped in a singlet shirt on Thursday morning.
The bottlenose dolphin was spotted in Koombana Bay, Bunbury, with the pale blue shirt wrapped around it, the Department of Parks and Wildlife says.
It's unlikely the dolphin simply swam into it and instead wildlife officials say it was probably a deliberate act.
"This could have been catastrophic for the dolphin if it had covered its blow hole and restricted its breathing," the Department of Parks and Wildlife says.
"Unfortunately the animal has not been seen since."
Anyone who has seen the dolphin or knows anything about the incident is asked to contact the Department of Parks and Wildlife's Bunbury office.
Whoever is responsible for dressing up the dolphin could face a fine of up to AU$4000 under the Wildlife Conservation Act.