What sort of future are we creating?

The photographer behind a compelling image of a seahorse gripping a cotton bud in Indonesia says he hopes the photo will "affect people's lives and create a change".

The photo is one of the finalist images selected for the Natural History Museum's Wildlife Photographer of the Year competition, now in its 53rd year.

After the announcement, expedition leader and underwater photographer Justin Hofman shared the photo on Instagram, saying he wished it "did not exist".

"Now that it does, I want everyone to see it," he wrote.

"What started as an opportunity to photograph a cute little seahorse turned into one of frustration and sadness as the incoming tide brought with it countless pieces of trash and sewage.

"This photo serves as an allegory for the current and future state of our oceans. What sort of future are we creating? How can your actions shape our planet?"

The post appeared to resonate with a number of people, inspiring them to share their own stories of how it had impacted on them.

"Almost everybody has shared a personal reaction to the photo, asking how can we keep this from happening," he told the ABC, adding he had been attached to his computer or phone for "literally a week" trying to respond to everyone who had been in touch.

"Literally since last Tuesday, I've been putting in 18 hours a day on my computer, waking up when certain time zones start their days to make sure I'm on top of things."

Hofman hopes to share the photo with as many people as possible, to inspire them to make a change.

"The reason the photo has been accepted by so many people all over the world is because it doesn't require a caption," he said.

"You can look at it and you can figure out what's going on yourself. Whereas some other photos, like if you see a pile of rhino horns lying on the ground, you kind of need a caption on why rhino horns are all lying on the ground.

"So, when it comes to conservation photography or photojournalism, it doesn't need a caption — you can put it all together in your brain."

He said the response to the photo had given him hope the world could make a change, particularly with how it dealt with rubbish.

"It's an important photo … it's just, you're playing a numbers game, you never know when that one person who can actually afford to invest in a plastic recycling plant, happens to see the photo and it inspires them," he said.

"You never know so you've got to get to as many people as possible.

"It's amazing the amount of people that have contacted me from all over the world, it gives me a little bit of hope.

"I can't be that pessimistic when you have people from all over the world reacting, essentially changing the way they live."

How was it taken?

Hofman captured the photo in December while diving in Indonesia off the coast of the island, Sumbawa.

The 33-year-old was with a colleague who noticed the seahorse swimming nearby.

"We actually found the seahorse first and it was by itself. It was before the water changed direction, when the tide changed is when it brought all the debris and stuff," he said.

"I think the seahorse was right on the leading edge of that current line and we found it first and then a few minutes later some other debris — natural stuff like algae and seagrass — and the seahorse went to that and grabbed on to that little bit.

"But as the wind picked up a bit and the tide changed direction more that's when the bigger stuff — the plastic and sewage — started to slip through the area."

He almost decided not to take the photo, but that was when his "FOMO" kicked in.

"Part of it was boredom, I had been sitting in a boat for an hour doing nothing and another part was that I haven't really seen that many seahorses in my life," he said.

"So, you get this FOMO, this fear of missing out, and I guess I had that like, 'Ah I'm going to regret this' — I've been in situations where I didn't take out my camera and I've regretted it later.

He says it's not the first time he has seen the impact of rubbish in the ocean, reflecting back on a time he went snorkelling with manta rays in another part of Indonesia.

"These manta rays were feeding on the current line, because that's where their food is, and in this current line there were bits of plastic, a plastic bottle," he said.

"So, it isn't the first time I've seen something like this, it's just the only time I've been able to capture a compelling image of it."