Donsol, Philippines (CNN) -- "Welcome to Donsol, the home of the gentle giants," Alan Amanse says smiling broadly at us as we awkwardly scramble onto the traditional fishing boat.

"We have something must be followed; the rules about whale shark interaction."

He's delivered this speech countless times, but says he never tires of seeing newcomers eager faces. Donsol in the province of Sorsogon, Philippines, was once a sleepy fishing village, now it buzzes with excited tourists who flock here for what many later describe as a life changing experience -- swimming with the largest fish in the ocean, the whale shark.

I have to admit, I was filled with childish excitement I hadn't experienced in years.

"If I say 'Ok, let's rock and roll', its time to get in the water; that's my magic word, 'rock and roll'," Alan tells us, perched on the edge of the boat, a devilish twinkle in his eyes.
If we were late by about a month the story would be different. Maybe now we would be seeing whale sharks being slaughtered here, right on this beach.

He and the crew are experts at whale shark spotting, able to scan what to us looks like a blank horizon for signs of the sharks below the surface. Small boats filled with tourists dot the tricolor waters, the shoreline rolling hills of emerald green.

"Look, look right there," Alan points at what to me initially looks like nothing.

"Wow! Its huge, 3-meters-long, about 20 meters in front of us," I shrieked as I began to make out the dark shape moving along side our boat.

We jumped in, but only just barely caught a glimpse of the whale shark before it disappeared into the depths of the ocean. I should note at this stage that despite my initial reaction 3 meters isn't a "huge" whale shark, they can grow up to 20 meters in length.

In fact at 3 meters they are still considered young, and seeing small ones is a rarity we are told. The whale shark interactions are closely regulated; 6 tourists per boat, 1 boat per whale shark, and no more than 30 boats in the water at a time. Plus, we're briefed to swim 3 meters away from the head and body, 4 meters away from the tail -- one powerful inadvertent hit can cause serious damage.

We had a professional underwater cameraman, Rico, added on to our crew for the day. I envied his lung capacity, his ability to free dive for minutes alongside these majestic creatures, filming them from all angles while I gasped for air and struggled to keep up.

We end up spotting a total of four whale sharks, the last one huge and right underneath our boat. It stayed close to the surface as if bemused by the attention and splashing.

I managed to dive down and see its gentle eyes, upturned mouth formed into a permanent smile. All I could think was, "Wow". That short moment I had was special, as if nothing existed but me and this graceful animal.

Eco-tourism has changed everyone's life in Donsol. Alan tells us how he used to have to take on odd jobs -- driving a tricycle taxi, construction work, playing guitar at bars -- to make ends meet. Now he makes six times what he used to, enough money to put his two children through school, even university.

Like most people in these parts, Alan used to view whale sharks as pests, constantly getting caught up in fishing nets and overturning boats. He says they were also hunted by villagers from other areas.

"Before I am not thinking that we need to save the whale shark because we don't have an idea of the whale shark," he admits.

According to the World Wildlife Fund, whale sharks are coveted in many countries. Their meat can sell for up to $17 per kilo, their fins a staggering $800.

The attitude towards whale sharks here changed nearly overnight. Credited with helping to make that happen is Dave Duran, a charismatic, passionate cameraman turned diver. Twelve years ago he shot footage of the whale sharks and brought it to international spotlight, to the attention of the World Wildlife Fund, marine biologists and scientists.

Suddenly Donsol became a major research destination. Little is known about whale sharks, a major part of preserving the species is understanding their migratory routes and breeding habits.

Within three months of Dave going public with his footage the Philippine government issued a ban on fishing whale sharks.

"If we were just late for about a month or so the story would have been different," he tells us. "Maybe now we would be seeing whale sharks being slaughtered here, right on this beach."

Eco Solutions have covered many stories in the ongoing battle of preservation vs. destruction. Here the balance shifted in favor of nature.

"It's just a matter of luck," Dave says. "We gave [the people of Donsol] some sort of hope that eco-tourism could work in Donsol and they believed it."