There are hidden lochans in the heart of Scotland that rest like diamonds in a towering ring of corries.

Most of the mountain corries do not have the small basin lochs but the Cairngorms have the highest, and some of the best examples, with seven such lochs over 900 metres.

Lochan Uaine, north of Cairn Toul, changes from ice blue to ivy green depending on the seasons. Local legend says it turns a deep shade of emerald when the fairies turn up there to do their washing.

David Cooper, Richard Gaston and Kimberley Grant have been there.

The crooked gullies were still white with snow left over from the winter but snuggled up in their sleeping bags and peeking out of their tent door, they watched the shifting mists swirl around the sharp peaks.

It was one of many perfect moments they have dedicated two years of their lives to capture.

The trio of young adventurers are set to release a compendium of their discoveries called Wild Scotland, celebrating some of the country's most breathtaking sites.

The guide to the Highlands and Islands, one of Europe's fastest growing adventure holiday destinations, explores the hidden parts of its better known tourist areas, as well as many more remote regions rarely visited by tourists.

It includes more than 800 wild swims, ancient forests, lost ruins and hidden beaches, as well as inns, wild camping, local crafts, artisan whisky distilleries and wild places to stay.

For the trio, it's been a massive adventure, but after gathering up nearly a quarter of a million Instagram followers so far on their journey, the support for their work is there.

"As friends we've been going on these types of adventures for years," says David Cooper, 29, who is a student in Glasgow.

"A lot of things in the book you can probably do as a day trip, taking in multiple places.

"I've been to places like Canada where it takes a bit longer to have these type of adventures because everything is so far apart but here in Scotland you can to these amazing places and back again in a day."

David was working in a shop in Glasgow when he first met Richard, who was a colleague planning out his future career as a photographer.

Kimberley arrived on the scene through a mutual friend at the city's art school.

Their mutual love of the outdoors and photography made them instant friends, and their explorations since then are what have kept them together.

When they were approached by Wild Things Publishing to pull all their explorations into one book, they agreed at once.

David grew up on Shetland so had already known a life of wild walks and camping.

The mainland and the other islands, though, still threw up surprises he hadn't expected.

Together with his friends, they journeyed into mountains, found glens devoid of a single person and hidden waterfalls and pools perfect for summer swims.

The best beaches had to include Fidden on Mull, or Losgaintir on Harris. Even on dull or stormy days, the team knew how incredible a trip to the coast or out to the islands could be.

They ventured into sheltered rocky coves, photographed Dun Deardail and the ancient Dwarfie Stane on Hoy.

"It got quite intense at times, trying to fit everything in," says David. "We'd never done anything like this before, but we're proud of how it turned out."

Their ethos supports the recent rise in staycations, as more Scots choose to holiday in the UK rather than abroad to save money.

With the wealth of the wild on our doorstep, our adventurous trio say there's plenty on offer to keep wild hearts happy.

To many of Scotland's resident hillwalkers and explorers, there are many locations in the book that they will know well, but having them all in one place is like an addictive check list of glens still to explore and rock pools still to swim in.

The guide has suggestions on where you can go to explore lost ruins and castles, watch seabird colonies on dramatic cliffs or walk barefoot on white-sand beaches lapped by turquoise waters.

The friends recommend wild camping in flower-covered dunes, have found - on foot - the best places to wander alone through fragrant Scots pine, and where you can go to spy on deer shifting silently through the ancient undergrowth.

Canoeing around turquoise-blue inlets and bays is highly recommended as is drinking smoky whisky distilled from the local waters with friends in cliff-top bothies, a fire flickering in the hearth.

"Richard and Kim will have their own favourite places and moments but I've always enjoyed the southern Cairngorms," says David.

"There are also some brilliant things on the east coast which often get overlooked."

"We lived it," adds David, who says he has at least 400 copies of the book in his living room ready for their launch on May 5.

"Now we get to relive it as we see others just starting the journey."