Singer Noah Cyrus has locked herself in a glass box as part of a new Peta campaign to boycott Seaworld.

The 'Life's No Beach in Captivity' billboard features bikini-clad Noah trapped in the see-through cage on a sandy beach as waves lap the shore behind her.

PETA activists and Cyrus herself hope the powerful new ad puts pressure on SeaWorld bosses to retire their long-suffering orcas held captive to seaside sanctuaries.

The campaign poster photo was shot by top celebrity photographer Brian Bowen Smith.

"I love animals so much and to think that any animal would be trapped, it makes me so sad," says Cyrus. "It's like living in your bedroom for your entire life and never being able to go outside."

A spokesperson for the animal rights group states: "In the wild, orcas form complex relationships, work co-operatively to find food, and traverse up to 140 miles in the ocean every day. But orcas at SeaWorld are housed in incompatible groups inside tiny tanks... So far, 41 orcas have died on SeaWorld's watch, and six marine mammals have died at its parks this year alone."