The underwater images from this year's competition, chosen out of thousands of submissions from six continents, are particularly compelling, showing whales, sea lions, sea turtles, and other marine life in their natural habitats.
The contest also does its part to keep these habitats intact. The World Nature Photography Awards team plants a tree for every photo submission they receive and every print sold of a winning photo on their online store.
Here are nine underwater photos that earned top honors in this year's competition.
Tom Shlesinger's photo of a green sea turtle beneath the waves in the Galápagos Islands placed third in the Animals In Their Habitat category.
Second place in the Plants and Fungi category went to Martin Stevens for a photo of rainbow wrack seaweed taken at sunrise in Cornwall, UK.
Ferenc Lorincz's photo of a giant perch swimming past a shipwreck and a diver in Portugal won second place in People and Nature.
A photo of a jellyfish, taken in Italy by Giovanni Crisafulli, won third place in the contest's Underwater category.
Philip Hamilton won second place in the Underwater category for a photo of a humpback whale in Tonga.
A female orca swam through a school of herring in Norway in a photo taken by Andy Schmid, winning first place in the Underwater category.
Nicolas Remy won first place in the Animal Portraits category with a photo of a black anglerfish in Kurnell, Australia.
In first place in the Nature Photojournalism category, Celia Kujala photographed a sea lion playing with a piece of trash in Mexico.
Tracey Lund won the contest's grand prize, as well as the Behavior — Birds category, with a photo of two gannets in the Shetland Islands battling for a fish.