The bonnie banks of Loch Lomond

Scotland's first national park opens next week. It means a huge area of natural beauty will be protected for the future. But it hasn't all been plain sailing.

"What would the world be," asked the Victorian poet Gerard Manley Hopkins, "once bereft, Of wet and of wildness?" The poem was "Inversnaid", the name of a village on the eastern shore of Loch Lomond. The writer was a young man when the world's first national park was created at Yellowstone in the US. Scotland has had to wait exactly 130 years for a place to, as the poem goes on, "Let them be left".

Britain took up the idea of national parks in the town and country planning surge after the Second World War, when the Labour government set out to protect areas of wilderness where workers could enjoy the countryside; the first of many, the Peak District, served Sheffield and Manchester. But Scotland was left out, until now.

The newly designated Loch Lomond and the Trossachs National Park lacks the gushing geysers of Yellowstone. But the area north of Glasgow can match Wyoming in terms of spectacular landscapes. Royalty has long recognised the natural beauty around Scotland's largest loch, and, appropriately, the Princess Royal will officially open the new park on Wednesday, 24 July.

By British standards, the park is huge. Almost the size of Hertfordshire, it stretches from Crianlarich in the north down to Balloch on the southern shores of Loch Lomond, and from Arrochar and the Argyll Forest Park eastwards to Callander. The Highland boundary fault line bisects the area, ensuring sharply contrasting landscapes of steep braes and lush farmland.

Tourists first appeared in the Trossachs in the late 18th century, drawn by tales of the untamed scenery and rugged hillscapes. The millions of people who have enjoyed the area since then might well ask what difference the new designation will make to them?

National park status aims – to conserve and enhance the natural and cultural heritage; to promote sustainable development; to encourage understanding and enjoyment of the area; and to promote economic and social development of the people and communities within the park.

A tall order, by any standards, and one that is further complicated by the myriad of interest groups eager to see their own particular cause furthered. The immediate impact will be new or upgraded visitor facilities, and greater provision of ranger services. From a longer-term perspective, park status should ensure more careful maintenance of paths and shore-sides, and sharper eyes on commercial activities.

The most obvious new feature for visitors to Loch Lomond is the National Park Gateway and Orientation Centre, located within the Loch Lomond Shores development in Balloch. This new complex runs down to the water's edge, and is designed to resemble a modern Scottish castle. One part is a tourist information and orientation centre, with educational and ranger services; the second is where you go shopping.

The development has not been without controversy – local firms fear that it will take business away from them, and the design has been criticised for failing to integrate into the wooded landscape behind it. Seen from the loch, the stark white walls and concrete flank are in disharmonious contrast to the waves and trees around. The Maid of the Loch, a paddle-steamer moored alongside, is diminished. No one on my boat trip – Scottish, Italian or American – had a good word to say about the design. But when it rains, as it does occasionally in these parts, Loch Lomond Shores will be the most popular place in town.

If you don't want to look at a building, there are plenty of other directions to turn – most obviously to the water. Twenty-three miles long and four miles across at its widest point, Loch Lomond is enveloped by gently rolling Lowland hills, and the sharp bare crags of the Highlands to the north. Its western and eastern shores are very different – the first is bordered by the A82, the busy main road to Oban and Fort William. The main stops along this shore – Luss, Balloch, Tarbet, Ardlui – are small villages, but provide bases for venturing further. Loch Lomond's eastern shore remains largely undeveloped. The best way to enjoy it is along the West Highland Way, the 95-mile footpath to Fort William.

There's no match for seeing the loch from the water, however. Cruises leave from Balloch, Luss and Tarbet. These short excursions are a good way to compare the landscapes around the loch, and are the nearest many visitors will get to the 20 or so islands dotted around it. Boats of all sorts, including canoes and yachts, are available to hire, although anglers are not the only ones unhappy at the frequency with which speed-boats race along the water.

Enticing as it is, Loch Lomond is only part of the national park. Two other significant lochs and a lake are thrown in: a sea loch (Loch Long), Loch Katrine (source of Glasgow's water supply) and, to the south, Lake Menteith – Scotland's only body of water to be called a "lake".

The Trossachs, the epitome of the varied and dramatic Highland landscape, are worthy of a national park in their own right. Callander, not far from Stirling, is the best place to start. Ben Ledi rises above the town, its slopes wreathed in misty trails, while the Rob Roy and Trossachs Visitor Centre does a good job of describing the outlaw's life and times. The area is dotted with reminders of Rob Roy, from the cave where he is said to have sheltered beside Loch Lomond, to his grave in Balquhidder.

For many Scottish climbers, the Trossachs are the first taste of serious ascents. There are several peaks above 3,000 feet, plus hills such as The Cobbler (at 2,901ft not quite a Munro, but no stroll). The highest point in the national park is Ben More, near Crianlarich (3,852ft). The still mountain air can be deceptive: one evening last summer, a man proposed to his girlfriend on the 3,240ft summit of Ben Lomond. The question had been heard by every other person on the mountain – who all held their breath until the (right) answer came, then applauded – much to the embarrassment of the kissing couple at the top.

Rob Roy & Trossachs Visitor Centre, Callander: 01877 330342; National Park Gateway, Balloch: 01389 722199 (from 25 July); Trossachs tourist information centre (Callandar): 08707 200628; general enquiries about the National Park: 01389 722600, www.lochlomond-trossachs.org