On board a train, Tintin reads a newspaper article about seven explorers who have returned from a two-year ethnographic expedition in the Andes, where they unearthed the tomb of the Inca, Rascar Capac.

Rudolf Ernst Brünnow and Alfred von Domaszewski begin a two-year expedition to the Arabian Peninsula, including Petra.

The first glowing reports of country rich with thousands of game animals came in 1806 when Meriwether Lewis and William Clark returned from their two-year expedition.

Just before Roger leaves on a two-year scientific expedition to Africa, he asks for Cynthia's hand and she accepts, although she insists that their engagement should remain secret until Roger returns.

Three years later he set off for a two-year expedition through Australia, New Zealand, India, Central and South America, and East Africa.

Perhaps no exploration in American history has more famously combined intrepidity with scientific enterprise than the two-year expedition of Lewis and Clark from the Mississippi to the Pacific two centuries ago.

His most notable achievement was leading a two-year expedition (1849-1851) to survey the Great Salt Lake and its surroundings.

In July 2008 both Mirs initiated a two-year expedition to Lake Baikal, the world's largest freshwater reservoir.

To hear the mountain climber and adventurer Phil Buck tell it, his successful two-year expedition to reach the highest peak in each of South America's 13 countries was, well, a lot of fun.

Venter has circumnavigated the globe and thoroughly explored the West Coast of the United States, and completed a two-year expedition to explore the Baltic, Mediterranean and Black Seas.