Tilly was swimming with local kids in Fiji when one detail caught her eye

Sydney teenager Tilly Cooper was on holiday with her family in Fiji when she noticed something unusual while swimming with local children.

Her family has a long history of visiting the tropical island, having holidayed there for decades.

"It's quite cool because my mum, when she was my age, used to go over there for family holidays with her mum and dad," Tilly, 13, tells 9honey.

Watch the video above.

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"So she became really close with the local villagers because at the Fiji Hideaway Resort and Spa, they hire a lot of people from the local village."

Her grandmother befriended one woman in particular, and the two families remained in touch ever since.

It was only natural Tilly and her family would head back to Fiji for her grandparents' 60th anniversary.

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"So they were renewing their vows and as it was incredibly hot with that humid weather and they [the locals] all invited me for a swim."

While they were swimming, Tilly noticed all the local children were jumping in dressed in everyday clothes.

At first she thought they didn't want to waste time retrieving their swimmers from home before jumping into the water.

Later she noticed local adults also entering the water fully clothed, including while fishing and participating in other water activities.

It wasn't until she'd returned home that Tilly came up with an idea to source swimwear for the local residents her family had formed such close bonds with.

"I thought, 'Well, I have connections with the Upper Northern Beaches Surf Club'. So I thought a swimwear drive would be really good."

Tilly's father and grandfather are both members of the surf club and so too is Tilly.

"I've just grown up there and then I've just received my SRC (Surf Rescue Certificate), which is what you get to become a surf lifesaver," she shares.

Her swimwear drive was an instant success, with locals and local businesses alike donating swimwear to the cause.

Tilly says when speaking with one of the general managers at the resort she was told that to own swimwear is a "huge privilege".

She was also told about the need for googles and wetsuits.

"They did fishing basically with their eyes closed because they can't see. And in the cold weather, they're freezing."

Tilly has also managed to source over 300 pairs of googles as well as wetsuits and rashies as the local culture is one of modesty.

"So obviously when surf clubs get new sponsors, their sponsors go on the rashie," she explained, adding the retired items would be thrown away.

Now, they have also been donated and are on their way to Fiji.

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The plan is to ship the swimwear collected to the resort. Then, next month, when the family returns to Fiji once more, they will assist with the distribution of them.

"We reckon we'll have about two villages there to supply because we've gotten a heck load of swimwear," she says.

To donate to the cause contact Mona Vale Surf Club.

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