The 2016 competition has now closed for entries. Thank you to all who have taken part this year. Over the next two months your images will be reviewed by some of the leading figures in nature and wildlife photography. It's an exciting and nail-biting time for all.
We'll be in touch in March if you've made it to the second round, and in May with results.
The competition closed for entries on 25 February 2016 at 11.30 GMT.
If you've made it to the second round, original and high-resolution files will be requested of you from 29 March until 11.30 BST 8 April 2016.
Winners will be contacted by 13 May 2016.
There are 16 adult categories.
Read the rules before entering the competition and submitting images.
Available to download in 12 languages.
Answers to the most common questions.