National Geographic's 2017 Nature Photographer of the Year contest is underway. Photographers around the world are invited to submit their work at natgeo.com/photocontest in any or all of four categories: Wildlife, Landscape, Underwater and Aerial.

The grand prize winner will receive $10,000 (about £7,500), publication in National Geographic Magazine and a feature on National Geographic's Instagram account, @natgeo. Entries close on Friday 17 November 2017, and the winners will be announced in December 2017. For details and official contest rules, please visit natgeo.com/photocontest. IBTimes UK showcases some of the most spectacular entries submitted over the past two weeks.

National Geographic Nature Photographer of the Year
Don't come any closer by Marc Hornig: An Orange Anemonefish (Amphiprion Sandaracinos) – most commonly known as 'Nemo' – was shot among this vibrant, iridescent and highly toxic anemone. This reef habitat was situated in the pristine waters of Sipadan Island, Sabah Borneo Malaysia.Marc Hornig / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
There is always room for one more by Eivor Kuchta: How many mountain goats can fit on this rock, if you start stacking them on top of each other? Mount Evans, Colorado, USAEivor Kuchta / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Over the lake by Phillip Chang: The picture was taken from a helicopter over lake Natron in Tanzania. A flock of flamingos were flying over the lake.Phillip Chang / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Nurse shark at Bimini by Christian Vizl: Portrait of a nurse shark swimming in mid water in Bimini, Bahamas.Christian Vizl / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Whale shark and anchovies by Steve De Neef: A whale shark and school of anchovies swim by at Mafia Island, Tanzania. The shark and schooling fish are often seen together as they both are after the same planktonic prey, sergestid shrimp. The population of whale sharks here is quite unique as they remain here year round. Scientists believe this is because there's an abundance of food around the island.Steve De Neef / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Lightning bridge by Alexis Darden: Spectacular view of the Golden Gate bridge during a Bay Area lightning and thunderstormAlexis Darden / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
In Transit by Christine Lai: This is a leopard who walked past our vehicle in the Okavango Delta. I admired the intensity of this leopard's eyes as it moved quietly through the grass.Christine Lai / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Smile for the camera by Gary Peart: Heart racing, hands clenched on the handles of my camera housing, peering through the silty mangrove water. The American Crocodile suddenly appeared out of the murk, almost resting its snout on the dome port of my underwater setup. I told myself to remain calm, that I was completely safe behind my camera. although it was a tense encounter at first the silty water adds to the dramatic nature of this image. a moment I will not forget in a hurry.Gary Peart / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Up in the Clouds by Damilice Mansur: After a long flight from Aruba to Canada and countless hours of driving, I finally got to Bonaventure island to be able to witness more than 54,000 breeding pairs of northern gannets. After 4 km of island hiking you can start to hear the sounds and even smell of the gannets. It was a beautiful day which made this capture seem like a the gannets were up in the clouds. the background fills the frame with hundreds of gannets and a clear blue sky.Damilice Mansur / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Over Glacial Waters by Shane Kalyn: As we flew over the beautiful Holmes River, the glacial waters contrasted nicely with the forest– the water extra blue due to increased glacial melt.Shane Kalyn / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
The Nyakamwe family of the DRC by Shannon Hinson-Witz: New mom Kanyarunka shields her baby from a rambunctious toddler.Shannon Hinson-Witz / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Kamokuna ocean entry, November 2016 by Grant Kaye: Lava flows into the ocean at sunset, Kamokuna, Kalapana, Hawaii.Grant Kaye / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Atlantic Puffin by Harry Collins: An Atlantic Puffin on the remote nesting island of Machias Seal Island off the coast of Maine. Harry Collins / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
The New Continents by Dragos Pirvulescu: An aerial view over the swamps of Cenas Tirelis near Riga, Latvia.Dragos Pirvulescu / National Geographic Nature Photographer of the Year contest
National Geographic Nature Photographer of the Year
Massai mara sunrise by Jay Ruan: A grazing wildebeest intersect with the rising sun.Jay Ruan / National Geographic Nature Photographer of the Year contest