British explorer Sir Ranulph Fiennes has set off to climb Mount Aconcagua in Argentina.
It's part of his record-breaking challenge to raise money for the charity Marie-Curie.
Mount Aconcagua is the highest mountain in South America, standing 6,959m high.
Check out the video to see which other mountains Sir Ranulph has climbed and which ones he's got left to conquer!
Sir Ranulph has already reached the top of Mount Elbrus in Europe, Mount Everest in Asia, Mount Kilimanjaro in Africa and, just last month, he finished climbing Mount Vinson in Antarctica.
The 72-year-old said it was "very demanding" due to the weather.
Sir Ranulph has two more mountains to tackle, Mount Carstensz in Australasia and Mount Denali in North America, to complete his challenge.
If he succeeds, he'll become the first person to cross the North and South Poles and climb the highest mountain on each of the world's seven continents.