Russian opposition leader Alexey Navalny has spoken out for the first time since his sudden disappearance several weeks ago, after his team said they eventually located him at a penal colony in Siberia Monday. Navalny, a staunch Kremlin critic, shared a message via his aides on social media on Tuesday, expressing "relief" after surviving what he said was a 20-day prison transfer that covered thousands of miles. "They brought me here on Saturday night. And I was transported with such precaution and on such a strange route (Vladimir — Moscow — Chelyabinsk — Ekaterinburg — Kirov — Vorkuta — Kharp) that I didn't expect anyone to find me here before mid-January," Navalny wrote on X, formerly Twitter. "The 20 days of my transportation were pretty exhausting, but I'm still in a good mood, as befits a Santa Claus," he said, adding that he is fine and "totally relieved" that he finally finished the trip. According to CNN's calculations, Navalny covered more than 3,700 miles (about 6,000 kilometers) in the 20 days his journey took, an average of 185 miles a day. Navalny had been imprisoned in a penal colony about 150 miles east of Moscow — until his lawyers revealed that on Dec. 11 they had lost contact with him. An intensive search effort followed — and on Monday they announced they'd located Navalny in the IK-3 prison colony in the village of Kharp, about 40 miles north of the Arctic Circle, in the Yamalo-Nenets Autonomous Region. His disappearance sparked immediate concerns for his well-being and came just days after Russian President Vladimir Putin announced he will run for re-election in March next year. Putin has de facto ruled Russia since 2000, becoming increasingly autocratic with each decade. Opposition figures like Navalny have been routinely jailed, silenced or fled into exile. Navalny is the best-known opposition politician in Russia. Throughout Putin's rule, Navalny has used his blog and social media to expose alleged corruption in the Kremlin and Russian business circles, and organized anti-government street protests. Even behind bars, his Instagram and Twitter accounts have kept up attacks on Putin with messages transmitted via his team. In his latest posts, Navalny said he had met with his lawyer, thanked supporters for their concern, and that he was doing well. His spokesperson, Kira Yarmysh, told CNN on Tuesday that Navalny's health was no worse than prior to his transfer, though the process was "very physically challenging." Navalny's posts on Tuesday suggest he remains in solitary confinement, though he did say he went for an outdoor walk in a yard. "I saw a convoy, not like in central Russia, but like in the movies — with machine guns, warm mittens, and felt boots. And with the same beautiful fluffy shepherd dogs," he wrote on X. "Thanks again to everyone for your support. And happy holidays!" Navalny was sentenced to 19 years in prison in August after being found guilty of creating an extremist community, financing extremist activities and numerous other crimes. He was already serving sentences of 11-and-a-half years in a maximum security facility on fraud and other charges he denies. Supporters of Navalny claim his arrest and incarceration are a politically motivated attempt to stifle his criticism of Putin. — CNN