National Geographic showcases 2017 travel photographer of the year

An erupting volcano, a ballet of swans, geometric architecture and a group of curious observers were just some of the subjects featured among the winners of National Geographic's 2017 travel photographer competition.

From the 15,000 entries, the Grand Prize was awarded to a photograph titled The Power of Nature, showing Mexico's Colima Volcano erupting with lava as it is hit by a bolt of lighting.

The hand behind the shot, Mexican Sergio Tapiro Velasco, took the photograph from around 12 kilometres away.

Mr Velasco had photographed the volcano for more than a decade and had been tracking its activity closely in the month leading up to the shot.

Mr Velasco told National Geographic he heard a booming noise and saw the biggest volcanic lightning he had ever seen. But it was not until he looked at the photos he had taken that he realised what a spectacular event he had captured.

"When I looked on the camera display, all I could do was stare," Mr Velasco said.

"What I was watching was impossible to conceive, the image showed those amazing forces of nature interacting on a volcano, while the lightning brightened the whole scene.

"It's an impossible photograph and my once in a lifetime shot that shows the power of nature."

Mr Velasco was awarded a 10-day trip for two to the Galapagos Archipelago, as well as a $US2,500 prize.

In addition to the grand-prize winner, top photos were selected in each of three categories: Nature, People and Cities.

National Geographic, a science, exploration, and adventure magazine featured all of the winners and honourable mentions on its website.