WILDLIFE and nature-based tourism is thought to be worth at least £400 million every year to Scotland's economy.
New figures have revealed the importance of whale-watching, angling, shooting and deer stalking to Scotland's 4 billion tourism industry.
Experts say growing numbers of visitors from home and abroad are discovering a wealth of activities on offer in Scotland's great outdoors. Scottish Natural Heritage has revealed it is to launch its biggest campaign to encourage tens of thousands of Scots to take advantage of what is "on our doorsteps".
Up to 200m is generated by activities like watching whales, sea eagles and ospreys, while country sports are thought to be worth a further 130m.
Research due to be published by SNH within the next few weeks will for the first time evaluate the impact of all activities from hill-walking to bird-watching.
One in four visitors to Scotland are said to go walking in the hills as either their main activity or as a major part of a trip.
Anglers alone are thought to spend around 113m every year, while deer management is thought to be worth some 105m. Whale watching is valued at around 10.7m, while Scotland's ospreys are said to generate 2.2m from tourists.
SNH claims a fifth of Scotland's industry depends on the natural environment and supports 242,000 full-time jobs.
SNH chief executive Ian Jardine said: "The country's stunning landscapes and wildlife attract tourists from near and far, and are consistently cited as the most important factor in drawing visitors to Scotland.
"Scotland is home to a diverse range of wildlife, including some of the largest and most important seabird colonies in Europe.
"The country has three-quarters of the UK population of red squirrels, and is the best place in the UK for viewing iconic species such as the golden eagle, puffin, bottlenose dolphin and red deer.
"More could always be done to promote Scotland's nature and landscape to visitors and to people who live here.
"We're developing a major campaign to encourage people to get outside."
Almost two-thirds of Scotland's wildlife and nature tourism operators reported an increase in visitors last year. VisitScotland has awarded umbrella body Wild Scotland a 36,800 grant to promote the country as a world-leading wildlife and adventure tourism destination.
A spokeswoman for VisitScotland, which has launched a "Perfect Day" campaign to attract more UK-based holidaymakers, said: "Feedback last year told us that around 21 per cent of people enjoyed bird or wildlife watching as part of their visit to Scotland so it's becoming a significant must-do activity for visitors from both the UK and overseas."
A spokeswoman for RSPB Scotland said: "Scotland has some amazing wildlife that draws crowds from all across the globe. We are extremely lucky to have iconic species like the golden eagle and the osprey right here on our doorstep."