When Al Hornsby, 66, was in school, his class wanted to build a saltwater aquarium and he volunteered to catch some fish.
He recalls: "We got our snorkels and masks and went down to the reef for the first time and that's all I ever wanted to do ever since."
Today, he is the senior vice-president of legal affairs for the Professional Association of Diving Instructors (Padi) Worldwide, an international scuba diver training organisation.
Earlier this year, he released a book, Face To Face Up Close With Mother Nature, of pictures of wildlife he has photographed over 29 years - from 1987 till this year - as well as the stories behind them.
He also founded Project Aware, an international non-profit organisation focusing on ocean conservation.
His book is a combination of all his passions, from diving to wildlife to conservation. He hopes that through it, he can show that "becoming familiar with wildlife is not only an exciting, breathtaking experience, but that it can also show you natural beauty that you may never have known existed".
And that "all this together can impress upon you and your children the need to protect our planet's amazing creatures and the environments within which they live".
Born in Tallassee, Alabama, in the United States and now based in Singapore, he attributes his appreciation for wildlife to his father.
His dad grew up on a small farm in Alabama and would take him out to the woods before sunrise, where they would sit against a tree and wait for animals.
"He would say, 'Now boy, sit quiet and be still and the animals will come see us. They know we're here, they're smart and they need to figure out if we are a danger to them.'"
His father was in the US Air Force and Mr Hornsby's family moved to Guam when he was 12. That was where he was first exposed to the underwater world and he has been hooked since.
Besides being a diver, he is also a photographer and writer, with articles and photographs published in publications such as Skin Diver and Sport Diver magazines.
He had considered other career paths.
"I had been accepted for a doctoral programme in counselling psychology, but I didn't get a fellowship for that.
"By then, I had already borrowed money and worked to get through school. It came to whether to get another student grant or be a diver like I always said I wanted to."
As for venturing into photojournalism, he says: "I asked myself what I wanted to do as a diver and realised that the guys who were doing the most interesting things in the dive industry were the writers and photographers."
1 What is your favourite place to dive?
I would say Sipadan island in Sabah, Malaysia. But these days, Indonesia is where the discoveries are happening.
For example, when you go to South Komodo, you have this explosion of life. When you get off the black beach and into the waters, the bottom looks like a lunar landscape. It's covered with soft corals of every colour and looks like someone splashed acrylic paint on a lunar landscape.
2 What is your most special dive memory?
The first was when I had a chance to go freediving with humpback whales in Tanga, Tanzania.
To be with those huge, gentle, intelligent creatures, it's life-changing. They were curious and would come to us near the surface, which was just an incredible experience.
The other was when I went to Okavango Delta in Botswana, a couple of years ago, to photograph the juvenile Nile crocodile.
Crocodiles are basically dinosaurs - they are so old and they are the only animals with humans as a normal part of their food chain. Even for sharks, humans are not their normal prey, so that puts crocodiles in a different category.
3 What is the hardest animal to photograph?
The crocodiles. The water was 13 deg C, visibility was 2 to 3m and the current was one to two knots, enough to sweep you away if you do not hold on.
There was the stress knowing that the result of messing up your entry and exit to the boat could mean a crocodile coming after you.
Then there was all of the setting up of the gears, while simultaneously trying to get to the side of the river.
4 Have you had any close shaves?
We were on our way to Aldabra, Seychelles, and it was a stormy night. We realised that there were thousands of tiny octopuses in the sea and decided to dive in to take pictures.
The boat had a swim step that could be lowered into the water for the divers to access the boat. The storm was causing that 100kg metal step to lift and crash back down.
I was on the surface of the water, setting up my gears and I did not realise that was happening.
In a split second, my snorkel was ripped out of my mouth. The swim step came down on top of me, but luckily, a cut was the extent of my injuries.
The irony is that after years of working with predatory animals, the only near-death incident was caused by a boat.
5 What is the cause that you feel most strongly for?
Shark and manta protection - that is one of the prime ones at Project Aware as well.
Another one I am involved in, and have been for a long time, is habitat protection. You cannot protect the animals without protecting the habitat.
6 What is your favourite photo?
I think of the one that, when I look at it, I feel moved the most. It is the humpback whale mother and calf.
Technically, it may not be the best of my shots, but with the sunbeams coming down, it made it look like a painting. It had a kind of ethereal feel to it.
7 Describe the best post-dive meal.
It starts with a beer, I think. And probably chicken off the barbecue and a bunch of vegetables, salad and fresh fruit.
I eat seafood, but when I'm diving, I do not want to eat my friends (laughs).
8 How would you like to be remembered?
I would like to be remembered as someone who was fortunate enough to find what he loved early in life and who then pursued it relentlessly.
•Face To Face Up Close With Mother Nature (US$49.95 or S$70.50) is available at www.alhornsby productions.com/store/.