Underwater Photographer of the Year 2017: Shipwrecks, killer whales and a giant octopus

French diver Gabriel Barathieu has been named as this year's winner, triumphing over 4500 underwater pictures entered from 67 different countries.

Underwater Photographer of the Year is an annual competition that seeks to celebrate photography beneath the surface of the sea, lakes, rivers and even swimming pools. The competition has 10 categories, testing photographers with themes such as Macro, Wide Angle, Behaviour and Wreck photography, as well as three categories for photos taken specifically in British waters. This year's judges were experienced underwater photographers Peter Rowlands, Martin Edge and Alex Mustard.

Underwater Photographer of the Year 2017: "Dancing Octopus" by Gabriel Barathieu (France)

French diver Gabriel Barathieu's photograph of a hunting octopus triumphed over 4500 underwater pictures entered by photographers from 67 different countries. The "Dancing Octopus" was taken in the lagoon of the tiny island of Mayotte in the Indian Ocean. Barathieu explains that he "had to wait for a low spring tide when the water was just 30cm deep (1 foot) so that the octopus would fill the water column. I got as close as possible with a wide angle lens to create this image, which makes the octopus look huge. Both balletic and malevolent, this image shows an octopus that really means business as it hunts."

British Underwater Photographer of the Year 2017: "Out Of The Blue" by Nick Blake (Ireland)

Taken in a freshwater sinkhole in Mexico, known as Chac Mool Cenote, Nick Blake said that his choice of location was "noted for the spectacular light effects as the sun penetrates the darkness." Continuing, he said that "I left my strobes behind for the natural light shot I wanted and positioned myself in the shadows of the cavern. Moving my eye around the viewfinder, I could see that the rock outline of the cavern around me made for a pleasing symmetry and I adjusted my position to balance the frame. The light show flickered on and off as the sun was periodically covered by cloud and as it reappeared, I beckoned to my dive guide, Andrea Costanza of ProDive, to edge into the illumination of some of the stronger beams, completing the composition."

Up & Coming Underwater Photographer of the Year 2017: "Oceanic In The Sky" by Horacio Martinez (Argentina)

Photographed in Egypt, this was Martinez's first Red Sea experience "we were on the last dive of the day and I ventured a tad deeper to get closer portraits of the Oceanic White Tips, when I noticed this shark patrolling in the distance. I took a few shots to expose for the sun beams and the surface, and was pleased by the dreamlike effect. Oceanics are great subjects for close ups as they are anything but shy. Yet, I wanted to capture their apparent loneliness in the big blue."

Most Promising British Underwater Photographer 2017: "Orca Pod" by Nicholai Georgiou (UK)

Taken in the depths of winter in northern Norway, Georgiou explained that "the days are short and the water is barely above freezing, but with orca around the cold is quickly forgotten. The light was beautiful as the sun skimmed the horizon, but the water was dark and foreboding. Then these orca swam by, nice and close. It was a moment, which will be hard to top."