A rehabilitated green sea turtle has been released back to the ocean in the US to mark Earth Day.

Several hundred onlookers watched on Marathon’s Sombrero Beach in the Florida Keys as staff from the Keys-based Turtle Hospital released TJ Sharp, a 65lb (30kg) juvenile sea turtle that was rescued in February.

The endangered reptile had been discovered floating offshore, unable to dive and visibly affected by fibropapillomatosis, a condition that causes cauliflower-like tumours and affects sea turtles around the world.

TJ’s condition upon arrival at the Turtle Hospital required surgical removal of the tumours and treatment with broad-spectrum antibiotics, fluids, vitamins and a nourishing diet of greens and mixed seafood.

“Sea turtles are the oldest animal known to man – to be able to take a sea turtle, rehabilitate it and return it to its ocean home on Earth Day, it’s just an amazing day,” Turtle Hospital manager Bette Zirkelbach said.

Ms Zirkelbach said that although Earth Day is recognised once a year, humans can take daily steps to protect marine resources and help ensure the survival of sea turtles.

“What people need to do to make every day Earth Day is to reduce single-use plastics, keep trash out of our oceans and help keep our planet clean,” Ms Zirkelbach added.