After more than an hour's hike through the hilly Bergslagen woods in central Sweden, excitement grabs a group of tourists when their guide points to the ground and whispers: "moose droppings!"

Reassured, the party of four lumbers to keep up with eco-tourism guide Marcus Jonson in their quest to spot one of these large-headed northern mammals, or perhaps even one of Sweden's elusive wolves.

"We have a chance to hear wolves because I know there is a family living in this area," says Jonson, "but when it comes to moose, I guarantee that you will see some!"

Jonson runs Kolarbyn which received Sweden's pioneering eco-tourism stamp of approval, Nature's Best, three years ago. The first of its kind in Europe when it was launched in 1996, the label is awarded to tour operators who meet a long list of strict criteria.

Today, 78 tour operators across Sweden, most of them small businesses like Kolarbyn, can boast the Nature's Best label. The certification process can take a year and the label can be revoked.

"The criteria are very tough, but they really helped me to improve my products and to prioritise quality over sales," says Jonson, 30, who only runs his business in the spring and summer months and spends much of the rest of the year traveling the world.