Apao is originally from Rotuma but grew up in his mother's village of Waitabu on Taveuni.
As Apao grew up, he never really understood the importance of the work his late mother Sala did, which is to manage the village marine protected area, now known as the Waitabu Marine Park as it is frequently visited by tourists.
Sala was the force behind the setting up of the park with the help of Marine Ecology Fiji Consultant, Helen Sykes.
After completing Form Seven on Taveuni, Apao enrolled at the Fiji Institute of Technology, but had to return to help his sick mother with her work. Sadly, she died in 2006.
Since then, Apao said, he has continued to do the work his mother did and has never regretted leaving FIT because he loved every moment at sea.
"She used to tell us the benefits of the work that she was doing but we never really bothered. We were also angry with her for leaving us many times and going overseas because of her work," he said as tears welled up in his eyes.
"But she was passionate about what she was doing and even though she had high blood pressure and was sickly she still carried on with her work. I tried to find out why she was so enthusiastic about the project so I involved myself in monitoring the area with other youth and people in the village.
"Through my participation I realised what she was doing was really important but sadly for me, she died after only seven months of working with her.
"But I will never forget the many things the marine park would bring us. She always reminded me the result of the work that I am doing will be reaped by me and the future generation in this village. And that we will have more fish and other sea food in our fishing ground if we continue to protect the tabu area.
"Now I see that what she was trying to tell us was right that what she was doing was for was for me and my children and their children's children."
The people of Waitabu are celebrating the 10th anniversary of their marine park which is one of the healthiest in Fiji.
Okostino is one of the 18 youths who is always on hand to assist visitors who want to snorkel. His hobbies include swimming and snorkeling, reading, and playing volleyball or rugby.
However, his involvement in the marine park will not prevent him from pursuing his studies. He said he will just stay on for a while until he knows that the project is well on its way before he leaves for school.
Okostino is one of the best tour guides at the Waitabu Marine Park and he knows what the park means to his people.
"It takes a long time for a reef to recover if it is abused and even corals are very important because they have those little animals on them that are very small and if one steps on the corals or break them it will affect those little animals," he said.
"What is important to know is that we do not know what is in the sea so if we protect the sea we also protect ourselves from getting hurt."
Before visitors go snorkeling they would be asked if they had snorkeled before and if not are taught how to use the masks and snorkel.
One of the guides will brief the visitors first and the first thing he would do is thank them first before the guidelines are stressed.
He said the visitors had to be thanked because they brought in money which helped the villagers protect their marine park.
"We tell them that they stay an arm's length away from the corals, clams, shell fish or corals. They should always try to stay afloat and watch from up there" he said.
"We also tell them that they are there to watch but not touch or take anything away from where it is even if it is a dead coral. And also to be careful that their fins do not break any coral."
Apao said the past 10 years of protection brought in more fish and invertebrate animals such as giant clams or vasua, vivili or trochus shells and bech-de-mer or sea cucumbers.
They have also grown to breeding sizes. Large schools of fish have eaten the seaweeds away and created clean rocks for new corals to grow, providing more places for small fish and other animals to live.
I was fortunate to be escorted by Okostino at the marine park and most times he had to tow me with a floater. Even though he is small in stature he was able to pull me along whenever the current was a bit strong.
But to watch all those different fish species swimming amongst those different coloured corals and with such big clams and trochus shells was awesome. And the incredible thing about the fish is they are so tame they do not even know that you are an intruder.
Unless one experiences this beautiful reef and its marine life, he cannot fathom the beauty of this marine park.
Okostino said he and his peers were aware of the importance of their marine park and he cherishes it so much that he said he could get violent if he knows of anyone poaching in it. He stressed they did not want what they had worked hard for to be taken away by inconsiderate and greedy people.
"It means so much to me that I would hurt anyone I see taking anything from the marine park and I will fight for it," he admitted.
"Now after 10 years of protecting our marine park we are so thankful for those who assisted us and also to our people and we do not want that go to waste."
- Ms Nakeke is an ocean science reporter with SeaWeb. SeaWeb is a non government organisation that helps the media promote a healthy ocean.