If you were going to kayak the length of the Missouri River, from source to sea, you’d probably start at a place called Three Forks, where the Missouri is joined by the Jefferson, Madison, and Gallatin Rivers. It’s not the true origin, but it’s close enough… for most.

Not so for Australian-born professional adventurer Mark Kalch. No, he started eight days north of Three Forks, high in the Centennial Mountains where he used snow shoes to trek up to a small spring coming out of the ground, because he couldn’t rest until he found the source. Why? Probably the same reason he took a two-month solo trip across Iran… on foot. That’s just the kind of guy he is.

For Kalch, the Missouri River is the second leg of a grueling 22,000-mile tour to paddle the world’s seven longest rivers on each of the seven continents, reports the Great Falls Tribune. Having completed the 4,300-mile Amazon two years ago, he moved on to the 3,900-mile Missouri in mid-June of this year and has estimated it’ll take him about three months to complete by reaching the Gulf of Mexico.

Kalch’s journey would be impressive enough if fueled only by a love of the outdoors and a hunger for discovery, but he’s upped the ante by adding a socially-conscious element to his mission. Aside from the sweet temptation of conquering an immense challenge, Kalch’s motivated by the opportunity to raise awareness about the importance of preserving the Earth’s rivers. In fact, he’s tackling the Missouri on behalf of American Rivers, an organization dedicated to protecting the country’s rivers and streams.

In his small vessel, Kalch, who funds his excursions through motivational speeches, sponsorships and adventure journalism, keeps two weeks of food, a sleeping mat, tent, maps, stove, clothes, water and safety gear.

Next up on his world river tour: the Nile in Africa, Asia’s Yangtze River, the Volga in Europe, the Murray-Darling River in Australia, and the Onyx River in Antarctica. If we had to bet, we’d say Kalch will do whatever it takes to find the exact point of origin at each and every one.