Ask most people to name a British national park and they’ll probably plump for the Lake District or the Peak District. But there are 15 parks in the UK, most of which receive far fewer visitors than those famous names. Here, we explore some of the best.

Bannau Brycheiniog (formerly Brecon Beacons)

Bannau Brycheiniog (the peaks of Brychan’s kingdom) national park is the highest ground in Britain south of Snowdonia and forms the centrepiece of the 519-square-mile region formerly known as the Brecon Beacons.

The Bannau, as they are known locally, have been a vital lung and escape for generations of miners and their families in the former coalmining valleys of south Wales since the last century, and the vast majority of the park’s 4.4 million annual visitors still come from there.

The Bannau’s Waterfall Country in the limestone belt on the southern edge of the park is one of its lesser-known attractions. The series of eight waterfalls near the hamlet of Ystradfellte are the finest, including the beautifully named Sgwd yr Eira (“spout of snow”), which forms a dancing curtain behind which you can walk without getting wet.

Llyn y Fan Fach is a mysterious, hidden lake cradled by the huge sweeping precipices of Bannau Sir Gaer (749 metres), one of the highest points of the Black Mountain (Mynydd Du), in the wild west of the park.

The legend of the Lady of the Lake concerns a young farmer’s son from the nearby village of Myddfai who, as he rested by the rocky lake shore, was amazed to see a beautiful young girl emerge from the lake. He immediately fell in love with this vision of loveliness and vowed to marry the fairy princess. However, she warned the lad that if he struck her without cause three times, or touched her with cold iron after they were married, she would return to the lake. Inevitably, that’s what happened.

Perched romantically atop a great limestone crag nearly 90 metres above the River Cennen near Llandeilo, the dramatic, broken-toothed silhouette of Castell Carreg Cennen dominates the skyline for miles. The earliest castle was probably the work of a Welsh prince, but the imposing ruins you see today were built by a later marcher lord named John Giffard as a demonstration of his wealth and influence.

Visitors can get an idea of the way in which a medieval castle gradually developed into a fortified manor house at the little-visited Tretower Court and Castle on the A479 near Crickhowell. At its centre is Tretower Castle, built around the beginning of the 12th century in motte and bailey style and eventually replaced by the existing circular stone shell keep. Next door is the magnificent Tretower Court, a fortified manor house famed for its exquisite woodwork.

The Bannau always seems to have attracted visionaries and eccentrics. Author Bruce Chatwin captured the essence of the hamlet of Capel-y-Ffin in the remote Vale of Ewyas in his haunting 1982 novel On the Black Hill, a story about two bachelor brothers that Chatwin wrote after a stay on a local farm.

Capel-y-Ffin was also associated with two more enigmatic figures. Inspired by visions of the Virgin Mary, self-styled Father Ignatius was a 19th-century Anglican monk who built a short-lived monastery here. The monastery, now a private house, was later the home of the controversial artist and typographer Eric Gill.

Where to stay The Bear Hotel (doubles from £149 B&B) in Crickhowell is a 15th-century coaching inn with restaurant and 35 rooms.

Northumberland

The great Whig historian GM Trevelyan once described his native Northumberland as “the land of far horizons”, and there are few places left in England where you can gaze across great vistas of beautiful and uninhabited countryside with just the sounds of nature for company.

Northumberland national park has been described as England’s Empty Quarter, and with only about 2,000 permanent residents within its boundaries, it is the most sparsely populated park in the country and one of the least visited.

It covers 405 square miles of rolling moors and picturesque valleys, stretching from the Hadrian’s Wall world heritage site in the south to the wild expanses of the Cheviot Hills on the Scottish border.

To get a taste of Northumberland’s green wilderness, and what faced the unfortunate Roman legionnaires posted to this northern limit of their empire, it’s worth visiting the site of the Chew Green marching camp, a short walk from Alwinton.

Built around AD80 on the Roman Dere Street, the camp was a staging post for imperial troops marching north. You’ll need a bit of what archaeologists call “the eye of faith” to imagine what it must have looked like when thousands of legionnaires were encamped here, because all that is left is a series of low grassy ridges and ditches, best seen in morning or evening light.

Of course, the Romans were not the first to frequent these wild and lonely hills. One of the most evocative places to walk in the footsteps of those first prehistoric pioneers is at Lordenshaws, at the foot of the Simsonside Hills above Rothbury. This is the best-preserved prehistoric landscape in the national park, featuring an iron-age hillfort and one of the finest collections of cup and ring rock carvings found anywhere.

Holystone, on the banks of the River Coquet near Harbottle, takes its name from its mysterious Lady or Holy Well. This tree-embowered pool with a much later Victorian Celtic cross marooned at its centre is thought to be an early Christian site where Saint Ninian baptised his converts. Ninian was a Scots-born saint credited with bringing Christianity to much of northern Britain, long before the later missionary campaigns of Saints Columba and Cuthbert.

It’s a short walk, crossing six footbridges, from Bellingham (pronounced “Bellinjum”) through glorious oak woodland to reach Northumberland’s prettiest waterfall at Hareshaw Linn. This lace-like nine-metre cascade – “linn” is the local word for waterfall – is the perfect place to listen out for wood warblers and redstarts.

Of all Northumberland’s villages, Elsdon has to be the most fascinating. Grouped protectively round its extensive village green, Elsdon has a 14th-century parish church dedicated to Saint Cuthbert, Northumbria’s patron saint; a classic fortified pele tower dating from the days of the reivers (borders outlaws); and a perfectly preserved Norman motte and bailey castle at the grass-covered Mote Hills across the Elsdon Burn.

Where to stay The French-inspired Le Petit Chateau (doubles from £125 B&B) in Otterburn has 25 rooms, some with four-posters.

Exmoor

Exmoor, with its plunging coombes, deep wooded valleys, and crystal-clear streams watched over by brooding moorland, is one of the most intimate and least-visited of our national parks. Among the best places to see what Exmoor looked like before agricultural “improvement” are the extensive commons, such as those at Challacombe.

There are no fewer than 12 bronze-age barrows (burial mounds) running north-west along the heather-clad ridge of Challacombe Common on the western fringe of the park. Collectively known as the Chapman Barrows, these now fairly insignificant mounds represent a linear cemetery for long-forgotten chieftains who lived 4,000 years ago.

The Valley of Rocks, west of Lynton, is an Exmoor oddity. This little dry valley running parallel to the coast is ringed by jagged outcrops of Devonian rock, and feels as if it belongs more in Skye or the Highlands of Scotland than sleepy Devon. This is especially so when you see the flock of bearded feral goats scampering across the crags.

It is believed to have been created by the coastal erosion of a former extension of the East Lyn River, which now meets the sea at Lynmouth. The valley retains some of its original character, but the addition of a cricket pitch and car park has robbed the area between the crags of some of the primeval wildness it once possessed.

The remains of some prehistoric hut circles have been found in the Valley of Rocks, but perhaps Exmoor’s most famous claim to prehistoric fame is the Tarr Steps clapper bridge across the River Barle near Withypool. The 55-metre bridge has 17 spans crossing the Barle, and although it is certainly of an ancient design, it is known to have been rebuilt several times after the massive slabs were swept away by flood water.

A much gentler scene is presented by peaceful Woody Bay just along the coast from the Valley of Rocks. Once destined as a possible holiday resort, mercifully it is now a quiet backwater. The stream of Hanging Water runs down through thickly wooded cliffs to a lovely little waterfall that empties into the sea.

Seating only 33 people, Culbone church is thought to be the smallest parish church in England. It is unusually dedicated to the seventh-century Welsh saint Beuno. The original church probably dates from those Saxon times, but it has a 13th-century porch and a late 15th-century nave. The total length of the church is 10.7 metres and the nave is just 3.8 metres wide.

Where to stay Tarr Farm Inn (doubles from £180 B&B) is a 17th-century hostelry with nine rooms and award-winning food.

The Cairngorms

Britain’s largest national park is also the coldest, highest and one of the least visited. The 1,748 square mile park receives nearly 2 million day visitors a year, a similar number to Exmoor, which is less than a sixth of the size. So if you really want to escape the crowds, this is the place for you. The lofty central Cairngorm plateau encompasses more land higher than 1,000 metres above sea level than anywhere else in the country, and in winter is the closest Britain comes to Arctic conditions.

It’s a bit of a trek to get there from Mar Lodge estate, the National Trust for Scotland’s nature reserve, and should only be attempted by experienced hillwalkers, but the steely grey waters of Loch Etchachan, below Ben Macdui (Britain’s second-highest mountain), give a real taste of the semi-Arctic Cairngorms. At more than 900 metres above sea level, Loch Etchachan is the highest lake in the UK, and chilly enough to put off any but the bravest wild swimmer.

The Linn of Dee was apparently one of Queen Victoria’s favourite picnic spots when she stayed at Balmoral. It’s where the infant River Dee is channelled through a narrow cleft in the rocks via a series of crashing waterfalls on the Mar Lodge.

If you are as lucky as I was on my last visit, you may witness glistening, silver-sided salmon leaping and twisting their way up the foaming waterfalls on their incredible, and ultimately final journey to their spawning grounds upriver. It’s a sight to thrill the senses.

They call the massive, thick-trunked Scots pines of the Rothiemurchus Forest “granny pines”, because some of them are more than three centuries old. And they are nothing like the spindly pines of the south: these venerable giantesses are what’s left of the ancient Caledonian Forest, with wide, spreading crowns and a beautiful, salmon-pink bark that glows in the setting sun.

They are home to a cornucopia of wildlife, including the rare and elusive capercaillie (a Gaelic name that translates as “horse of the woods”), with its guttural, almost alcoholic-sounding, popping-a-cork call; the red squirrel, which finds a stronghold here among the protective “grannies”; and a rare finch, the Scottish crossbill, high up in the spreading branches.

The return of ospreys at Loch Garten, near Abernethy, is a great Cairngorm success story. They had been extinct in Scotland since 1899, but a Scandinavian pair was seen nesting atop a dead tree by Loch Garten in 1959, and the RSPB decided the best way to protect them from egg thieves was to use the public as watchdog wardens. So it set up an observation centre about a quarter of a mile from the nest, but with a clear view of it, aided by CCTV cameras. There are now thought to be between 250 and 300 breeding pairs of ospreys in Scotland.

Although peaceful enough today, the straths, glens and corries of the Cairngorms were the scene of bitter warfare between the clans and the Hanoverian English Crown 300 years ago. This is vividly illustrated by the substantial hilltop roofless ruins of the Ruthven Barracks, alongside the B970 between Kingussie and Drumguish. Following the uprising of 1715, this former clan stronghold was converted into barracks for 120 troops and 28 horses in 1721, in an attempt to subdue the rebellious Highlanders.

Where to stay The Mountview Hotel (doubles from £120 B&B) in Nethy Bridge has 11 rooms and a restaurant for residents only.

North York Moors

The high shoulder of the North York Moors, midway down the east coast of Britain, is usually among the first to be hit by winter snowstorms as they funnel down the North Sea from the Arctic. But in late summer, the bleak expanse of the high moors is replaced by a royal-hued purple sea of rolling heather – the finest display of this hardy moorland plant in the country. Heather moorland covers about 35% of its 554 square miles, and was one of the main reasons for its designation as a national park in 1952.

A good way to appreciate the topography of the North York Moors is to stop at the convenient layby on the A169 Malton to Whitby road, where you get a grandstand view of the heather-fringed Hole of Horcum. This 120-metre-deep cauldron was created when springs welling up from the hillside gradually undermined the slopes above, eroding the rocks.

Mallyan Spout, near Goathland, is the highest and prettiest waterfall in the national park, and a short walk from the village. This 21-metre slender cascade in the West Beck is carpeted with lush mosses and lichens, and set in deep ancient woodland.

Meanwhile, Farndale, which is surrounded by some of the wildest moorland in England, is renowned for its springtime display of wild daffodils. The three-mile walk between the two hamlets of Low Mill and Church Houses on the banks of the River Dove is a delightful stroll through those golden-trumpeted harbingers of spring.

Simon Jenkins, in his guide to England’s Thousand Best Churches characterises St Mary’s Church in Lastingham, near Kirkbymoorside thus: “Some churches are a challenge to the faithful. Lastingham is a challenge to the faithless.” The mainly 11th-century building is remarkable for its unique, cell-like crypt, which has two Romanesque aisles, a chancel and an apse. Whatever your religion or lack of it, it’s a place where it seems the very air you breathe is redolent with ancient sanctity.

Although he is usually associated with the seaside town of Whitby, the 18th-century round-the-world explorer James Cook is most prominently commemorated in the 18-metre high sandstone monolith of the Captain Cook’s Monument on Easby Moor, above his childhood home at Great Ayton. The Cook family moved to Great Ayton in 1736 and James went to school in the little building that is now the Captain Cook Schoolroom Museum. The explorer’s parents would later build a cottage in the village, which was dismantled, shipped across the world to Australia – perhaps Cook’s most famous “discovery” – and rebuilt in Melbourne in 1934.

Where to stay The Fox and Hounds (doubles from £129) in Ainthorpe is a 16th-century inn offering 10 bedrooms and a restaurant.

Roly Smith’s latest book is Short Walks to Curious Places (Conway/Bloomsbury, £20). To order a copy go to guardianbookshop.com