Ashley Wee, 26, won the £5,000 top prize with an image she captured off the coast of Nassau, Bahamas.
The environmental photography contest was organised by the Prince of Wales’s International Sustainability Unit and open to Commonwealth citizens.
Commenting on the photo, Ashley – a biology graduate who had spotted a group of six or seven turtles while snorkelling – said: ‘As we drifted within a few feet of them, these turtles were not disturbed by human presence as they maintained a quiet and natural demeanor.
‘One in particular caught my attention, as it was bobbing at the surface.
‘It made me think about this animal and how it was affected by things both above and below the ocean.’
Hanli Prinsloo, a free-diver and one of the judges, said: ‘What immediately captivated me… was the implied vulnerability of the animal. The neck stretched up to the sky, the mouth slightly open and the implied gasp for air.
‘In many ways, for me, this embodies the state of our oceans: vast, simple but vulnerable.’
Ashley received her award from the Prince of Wales at the Maritime Museum in Malta.
The Prince of Wales said the number, quality and thoughtfulness of entries ‘left me in no doubt as to the broad support that exists for doing things differently’ concerning the state of oceans worldwide.
The best images can be viewed HERE.