These pictures show the moment a disgruntled crocodile realised he was having his picture snapped.
The crocodile snuck up on the photographer, Octavio Aburto, as he took underwater photos in Mexico.
Octavio used his 20-year experience - and a lot of bravery - to keep his cool and take the pictures of the croc's toothy grin.
He told Caters News: "I had around 3 or 4 metres of visibility, so when I saw the crocodile for the first time, it was almost in front of me.
"I had to stay calm so the crocodile didn't detect my presence.
"I just put my camera between the crocodile and me, and I started taking pictures while the animal was trying to come back to its refuge."
The 40-year-old was part of an expedition in 2013 to Banco Chinchorro, a group of islands and coral reef in the Mexican Caribbean.
The atoll has the purest population of American crocodile - Crocodylus acutus - and has more than 250 living there.
Mr Aburto wanted to get some great shots of the crocs but he didn't expect to get as close as he did.
He said: "It was almost dusk and I was able to take the pictures with a very nice light, but also I had to take some of them with very slow speed, so the movements of the crocodile was captured in a great way but maintaining the magnificent teeth that the animal has."
Octavio has been a professional underwater photographer since 1994 and is now also a researcher at Scripps Institution of Oceanography.
He said: "I have not done this before, but the experience was incredible. I really think that the animal was surprised in the same way that I was.
"Although there was very little time to think about what was happening, I never felt that the animal would attack me."