Parents who have who have hit rock-bottom trying to keep their kids entertained these school holidays can rejoice.

There's a new craze in Tauranga that's basically free and gets the kids out enjoying the fresh air.

It involves painting designs – from the simple to the intricate – on small rocks, before hiding them in public places such as parks and reserves.

The fun is waiting to see if someone finds your rocks, as well as the challenge of hunting down those hidden by other people.

Its popularity is confirmed by the Tauranga Rocks Facebook group, which has over 2000 members. Lisa Millar started the group after becoming hooked on the craze in Wanganui.

'We were there on Boxing Day visiting my mum and she got us into it. The four of us – her, me, and my two children – spent the whole day painting stones. Then we went out and had to find inventive places to hide them.”

Lisa says when she returned to Tauranga, photos kept popping up on her Facebook feed of people who had found the rocks she and her family had hidden in Wanganui, prompting her to start a group up here.

Within a few days it had 600 members.

'It gives kids such enjoyment,” she says. 'It's about the buzz of the hunt, and the buzz of creating something for someone else.”

Tauranga mum and early childhood teacher Stacey Mckellar Murphy thinks it's a fantastic way to get kids out and about in the community.

The girls with all the rocks they've painted.

'I joined when there was probably 39 people. It's been a great thing to do. I love that it's free, and we're going to parks we've never been to before. I love how the kids spent about four hours a day painting rocks. When you have kids in Tauranga there's not a whole lot you can do for free, but this has been fun.”

Her daughters were at Yatton Park on Wednesday hiding rocks, and finding them too. At home they've been using nail polish to paint theirs, which this reporter can confirm is top quality stuff for painting rocks.

So, why not get a little boulder and try it out?

SunLive reporter Ryan Wood tries his hand at the rock craze, producing this collector's item. Find it at No. 1 The Strand.