Karl Bushby was 29 when he left his 5-year-old son in England, flew to the bottom of South America, and started walking home. That was in 1998. He's 57 now, and still walking. He set himself two rules: no transport of any kind, and no going home until he reached England on foot from the south. The full route is 36,000 miles, about one and a half trips around the world. He's covered roughly 30,000 so far. He walked the deserts of northern Chile, where water was sometimes days away. He floated down a river in Colombia hidden under a pile of branches. The jungle was crawling with FARC fighters, armed rebels who would have killed him on sight. They passed within feet of him once. He did 18 days in a Panama jail for entering without a visa. The army flew him there in a helicopter. When they let him out, they took him back to the exact spot of his arrest so he could walk those miles too. In 2006 he walked across the frozen sea between Alaska and Russia. It took 14 days with one partner. They jumped between floating chunks of ice and swam the gaps in survival suits, in water cold enough to kill a man in minutes. They climbed 30-foot walls of ice piled up from collisions. The wind kept blowing the ice the wrong way. When they crawled onto Russian soil 52 miles north of where they'd meant to land, border guards were waiting and arrested them on the spot. In 2013, Russia banned him for five years. So he walked from Los Angeles to the Russian Embassy in Washington DC in protest. About 4,800 km on foot, roughly the width of the United States, just to make a point. They lifted the ban. When he couldn't get a visa for Iran, he swam the Caspian Sea instead. 179 miles, 31 days, with one other walker and two Azerbaijani swimmers. His father Keith has been running things from home for 27 years. Asked recently how he'll feel when Karl finally makes it back, he said: "I'll be glad he's done it. But it will be strange to not have him out there." He's walking through Austria now, along the Danube River, with about 1,000 miles left. He hopes to reach the English Channel by September. After that, he needs special permission to walk through a service tunnel under the sea between France and England, since he hates swimming and a boat would break his own rules. He told BBC Radio last summer: "Getting home, I just don't know, it's weird. It's a very strange place to be in, where suddenly your purpose for living will have a hard stop." If he makes it through that tunnel, there will be a line of footprints stretching from the bottom of South America to a small house in the north of England. The son he left behind will be 33.