(CNN) -- The life-blood of civilizations and natural wonders, rivers are one of the best ways to explore the world's most spectacular scenery.
Carving their way through the heart of vibrant cities, ancient areas and untouched wilderness, rivers offer a unique insight into diverse lands, cultures and people.
We've picked some of the world's greatest rivers to profile -- the longest, deepest, widest or simply the most beautiful.
Whether you're after pristine isolation, lush wilderness, exotic animals or the bustling color of vivacious port towns, sailing down these great rivers can take you there.
Route through Peru and Brazil, South America
Big, wild and wondrous, the Amazon River, the largest in the world, is home to the most expansive and diverse rainforests on earth.
Accounting for approximately one fifth of the world's total river flow, it is teeming with strange, rare, exotic and endangered wildlife including piranhas, pink river dolphins and the infamous anaconda snake.
As well as the largest number of freshwater fish species in the world (topping 3,000), the river gives life to an amazing array of plant life from orchids to bromeliads and palms.
Most routes start in the port town of Iquitos, Peru and journey downstream into Brazil stopping at the port towns of Manaus and Boca de Valerian.
With such a vast expanse, the highlights are many. They include the "meeting of waters" six miles from Manaus, where the black Rio Negro River meets but doesn't mix with the brown waters of the Amazon -- a truly incredible display of nature.
Route through Egypt, Africa
If legend is to be believed, the Nile once transported a baby Moses to the Pharaohs and Cleopatra to her Anthony. Imbued with centuries old history, it conjures tales of adventure, romance and mystery.
The longest river in the world, the Nile has, for thousands of years, been the lifeblood of Egypt, cultivating an entire civilization on its banks.
With the desert as its backdrop, the river carves through the sands like a giant open-air museum, snaking its way past 2,000-year-old temples and ancient relics.
Traveling in traditional pointy-sailed feluccas, the most popular trip is from the city of Aswan -- Egypt's gateway to Africa -- downstream to Luxor, known as the city of "palaces."
The journey is dotted with ancient temples, enough hieroglyphics to fill a museum and even some mummified crocodiles and is the same route taken by the likes of former British Prime Minister Winston Churchill and authors Mark Twain and Ogata Christie, not forgetting the Pharaohs.
Route through Germany, Austria and Hungary, Europe
A source of inspiration to generations of artists including composer Johanna Strauss and author Jules Verne, the Danube River could be called Europe's Classical River.
Originating in the Black Forest in Germany, the great river winds its way through some of Europe's most spectacular medieval and renaissance cities -- traversing eight countries before finally emptying into the Black sea.
World heritage sites and areas of outstanding beauty litter the rivers' banks. Highlights include the 1st century town of Bamberg, Germany -- famous for its smoked beer -- the baroque buildings of Linz, Austria, the elegant splendor of Vienna, and the gothic architecture of Budapest, Hungary.
In between the splendor of the cities, the Danube's banks are bejeweled with fairy-tale castles, Roman ruins, monasteries, ancient fortresses, vineyards and stunning natural scenery.
Route through India, Asia
It cuts through one of the most vibrant and chaotic countries in the world. The great Ganges River is the heart and soul of India, both economically and spiritually.
Stemming from the Himalayan Mountains, it is the largest river in the Indian subcontinent and also the holiest, mentioned in one of the earliest Hindu scriptures.
For many Hindus, the Ganges is an essential pilgrimage: Millions flock to its banks each year in order to bath in the holy waters and cleanse their souls of all sins.
To glimpse these massive gatherings, sail to the holy sites of Haridwar, Allahabad and Varanasi, where ornate and colorful temples hold swarms of people as they file in and out of the water.
Apart from its religious significance, the river is also part of everyday life for many Indians, where they wash their clothes and bathe, offering a unique insight into the people and their culture.
Route through China, Asia
A dividing line between north and south China, the huge Yangtze River has for centuries been China's main transport artery.
Flowing from some of the country's most remote regions into the heart of its modernized, industrial cities, the river crosses ten provinces covering some 6,300 kilometers.
A plentiful source of myths and legends, the river takes in some of China's most historic places: The famous ghost town of Fengdu, where the dead are said to migrate and the ancient city of Xian, renowned for its terra-cotta armies among them.
But, perhaps the most breathtaking of all is the natural beauty of the Three Gorges.
Now part of a controversial dam project to wean China onto hydroelectricity, the gorges are epic in proportions, with boats sailing through swirls of mist, abutted by towering cliffs and limestone ridges. Awe-inspiring stuff.
Route through the Democratic Republic of Congo, Africa
The star of Joseph Conrad's classic novel of imperialism and descent into madness, "The Heart of Darkness," a journey down the Congo River is not for the faint-hearted.
Deep in one of Africa's most tumultuous regions, the Congo has remained relatively untouched by tourism, and the modern day realties of life can be harsh.
But if you're after adventure and choose your route and guide sensibly, you'll be rewarded by scenes of outstanding natural beauty in one of the world's least-explored areas.
The traditional route for travelers is from the towns of Mbandaka to Kisangani -- both founded by the explorer Sir Henry Morton Stanley in the 19th century.
On this route the river, which acts as a massive drainage channel for the rainforests of the Congo Basin, passes through Yangambi Biosphere Reserve, which is home to 32,000 species of trees.
Another highlight is the town of Bumba, where the river stretches to its widest length, and which is blanketed in a multitude of water hyacinths.