Cameras focus on New Zealand's South Island, and the great Dunedin Railway's trains - the Inlander and the Seasider. The journey begins with a trip down the Taeiri Gorge towards Otago Harbour, and the area's capital, Dunedin. Bill Nighy narrates.

The Cambrian Line starts in Pwllheli and travels 200km to Shrewsbury, taking in the fairytale village of Portmeirion, the seaside resort of Aberdovey and the ancient capital of Wales, Machynlleth.

We travel on one of the oldest steam railways in Australia, the Zig Zag Railway and on a coast-to-coast journey aboard the iconic Indian Pacific, where cameras focus on the spectacular Blue Mountains.

Exploring the Far North Line, starting from Inverness in the Highlands of Scotland.

The New Zealand South Island line scales the snow-capped Southern Alps, travels through Maori hunting grounds and finally reaches Christchurch, a city sitting on a volcano.

The 200-mile Ligne de Cévennes, which travels northwards through the Massif Central to France's volcanic heart - Clermont Ferrand and the spectacular Puy De Dome. The route takes travellers across three incredible historic viaducts, plunges deep underground to explore the area's hidden wildlife and traverses through several impressive valleys. The route winds through one of the world's most spectacular national parks, before reaching its final destination, a collection of 80 dormant volcanoes.

New Zealand's Northern Explorer, the longest-running passenger service in the country. The train travels 423 miles along the historic North Island Main Trunk Line on a 12-hour voyage and the journey takes travellers through some of the most astonishing landscapes of the southern hemisphere from volcanoes to coast and from lava fields to unspoilt islands. Historians explain the history of the railway and tell the tale of the terrible tragedy at Tangiwai, when over 150 people were killed by a volcanic mudflow that hit the train.

A 600-mile journey through one of the most world's most northern countries - Finland - from Helsinki in the south to Kemijärvi in Finnish Lapland. The line whisks passengers through the thickest of forests, past vast frozen lakes 63 times the size of Lake Windermere and to station stops where time has stood still. As the train enters the Arctic Circle, it calls at Rovaniemi, a place destroyed by German soldiers at the end of the Second World War. Now the town has been re-built, famously in the shape of a reindeer, serving as the official home of Santa Claus.

A look at Bavaria's rich history of steam travel, seeing world-beating miniature railways and visiting a whole host of interesting places on a journey to the heart of the Bavarian Alps, where a beer-brewing monk and a town made famous by the Winter Olympics await. Later, a trip to Germany's highest mountain Zugspitze - which offers amazing panoramic views right across Germany and Austria.

A 500-mile journey across South Africa in a luxury hotel train, which travels between Pretoria and Durban on the coast over the course of three days.

A trip through Devon to the tip of Cornwall, going back in time to recapture the golden age of luxury train travel. Travelling in the elegantly restored Statesman, passengers relax in its vintage carriages and enjoy the exquisite service. The first stop is on the stunning Devon coast, which suffered devastating destruction during the heavy winter storms of 2014. From Dawlish, it heads to Cornwall and across the Royal Albert Bridge, a masterpiece of railway engineering.

The West Highland Line is one of the world's truly legendary train routes, crossing spectacular Scottish moors and mountains as it heads towards Skye. Starting in Glasgow, it glides towards Loch Lomond, the world's largest inland stretch of water. It then sweeps north to enter the wild and windswept landscape of Rannoch Moor. After ascending to Corrour, Britain's highest station, the journey passes Ben Nevis, the UK's tallest mountain and then across the famous Glenfinnan viaduct. The coastal town of Mallaig is gateway to the Isle of Skye with its world-famous Highland cuisine and many breathtaking views.

In Anchorage, Alaska, cameras focus on flagship service the Denali Star, a luxury passenger train and part of the great Alaska Railroad fleet. The vehicle then heads north along the Knik Arm, and crosses this huge sea inlet to enter the vast wilderness of Alaska, America's largest and remotest state.

Pulled by a gleaming Siemens Charger locomotive, our double-decked coaches will take us on a 350-mile trip into the Californian dream. On our way we'll stop off in Carlsbad.

Starting from one of the world's most remote cities, Walvis Bay, in Namibia, we roll 1,500 miles through the Kalahari desert to Pretoria, South Africa's Executive Capital.

Canada's iconic Rocky Mountaineer train loops from Vancouver to the heart of the Rockies via crystal clear lakes, lush coastal rainforest, and the splendour of the Fraser Canyon.

Beginning in the mountaintop town of Creel, the Chihuahua Pacifico Express - or El Chepe for short - winds its way through the Tarahumara Mountains, home to the reclusive Raramuri people. Divisadero, Mexico's most panoramic station, offers the first glimpse of Copper Canyon. Created by six separate yet conjoined gorges, it is four times the size of the Grand Canyon. The train continues on to the Urique Canyon, which at 6,200ft deep it is the deepest in North America. The final leg crosses the state of Sinaloa, Mexico's breadbasket, before reaching Los Mochis and the gateway to the Pacific Ocean.

Celebrating the wonders of Queensland, we travel over 1,000 miles (1,600 kms) from Brisbane to Cairns onboard one of the most advanced trains in the world.

A journey through Sicily that takes in seven Unesco World Heritage sites, with the first stop being a visit to a castle whose baron was inspired by Hampton Court. There's a meeting in Modica with Sicily's most famous chocolatier, a trip on the unique railway that travels around Etna, and a visit to Ragusa, a baroque-inspired city famous for its beauty and for its spiral railway that travels within a mountain.

A journey through the mountains of the Italian Riviera in a restored vintage 1920s train, beginning at Cinque Terre national park, and concluding in the historic port city of Genoa. Along the way, the train stops at the elegant resort of Santa Margherita and the remote 10th-century abbey of San Fruttuoso.

A ride is taken aboard the Northern Belle in and out of England and Wales.

The Northern Spain line begins near Leon in the Picos de Europa mountains, takes in Bilbao's Guggenheim Museum and the beautiful coastline of Galicia, finally ending in the spectacular harbour of Ferrol.

A trip beginning in Inverness and soon passing Culloden, the site of the last pitched battle on British soil. It then enters the Cairngorms National Park, home to some of Europe's finest landscapes as well as valleys steeped in Gaelic folklore. The park's station at Aviemore is home to the Strathspey Railway, where Victorian steam locomotives come to life. There is then a climb to the highest point on Britain's railway network before the train winds its way through Fife. Eventually the route crosses the Forth Bridge before arriving in Scottish capital Edinburgh, admired for its architecture and annual arts festival.

Luxury heritage train The Northern Belle, aka steam locomotive 6201 Princess Elizabeth, travels through England's rural north west. Beginning in Preston, the passengers of its stylish 1930s Pullman carriages are soon whisked up through Cumbria and the spectacular landscapes of the Lake District. The train continues on to historic Carlisle, the site of a world-class medieval cathedral and home to supposedly England's most haunted station. It then joins the Settle to Carlisle line, considered one of the most scenic railway routes in the world.

Escape with us aboard the magnificent steam train Tornado as it is coupled up with 13 luxury vintage carriages on a 6 hour journey through Yorkshire, to Northumbria and the Borders.