That Noah's Ark, or some remnant thereof, currently sits on Mount Ararat.
To preface this topic, I'm setting aside the question of whether a global flood really did occur, and was survived by a man named Noah and his family aboard a large wooden vessel called an Ark. I'm also setting aside the question of whether that vessel actually landed on Mount Ararat (singular) or somewhere in the mountains (plural) of Ararat, as actually stated in the biblical Book of Genesis, chapter 8, verse 4. Instead, I will assume that at some point in the ancient past, there really was an exceptionally catastrophic flood, a man remembered by the name Noah, and a vessel which came to rest somewhere on the singular mountain known as Mount Ararat. Even if all that is true, I believe that the chance of the Ark being there today is just about zero.
The reason I don't believe that Noah's Ark is currently on Mount Ararat, even if indeed it ever was there, has to do with the nature of glaciers. Glaciers, including those on Mount Ararat, don't just sit there, they move downward, along with anything unfortunate enough to be entrained inside them. If a flood were to carry a large vessel to the top of a mountain, it could remain in place for a time as the floodwaters recede. Eventually, as the world's climate returns to normal (or maybe finds a new normal), due to the elevation, the top of the mountain would be covered with snow. Over time, the snow would compact into ice, forming a glacier. The snow and the resulting glacier would gradually engulf the vessel. As the glacier moves downhill, it would drag the vessel down with it, along with rocks and other debris. Eventually, the entrained objects would reach a lower elevation where the ice would melt. Any large object made of wood, after being disgorged by the glacier, would be exposed to the elements. The wood which had formed the Ark could then be burned in a forest fire, be scavenged by humans, or just rot away. According to the various times and dates in Genesis, the Flood happened over 4,500 years ago. That's plenty of time for Noah's Ark, if it really existed and landed on Mount Ararat (singular), to have been dragged down the side of the mountain by a glacier, and then exposed to the elements by the melting of its lower end.
One modern example of something being engulfed and later disgorged by a mountainside glacier is an airplane which crashed into a mountain in Alaska in 1952, whose wreckage was found in 2012, as reported in the AirForceTimes.
That Jesus, during his "lost years", traveled to India or Tibet.
According to this story, a man named Issa travelled from the Middle East to India, where he studied Hinduism with Indian gurus, and then went to Tibet, where he studied Buddhism, before returning to the Middle East. This Issa is asserted to be the same person as Jesus of Nazareth, whom we see in the New Testament, which doesn't say anything about his life between the ages of 12 and 30, this period known as his "lost years". There has been much speculation about the events of his life during that 18-year period, including ideas about places to which he could have travelled. A sojourn in Tibet to study Buddhism, however, would be impossible, because Buddhism did not arrive in Tibet until the seventh century, i.e., about seven hundred years after his lifetime. Moreover, when citing scripture, he always quotes what today is called the Old Testament. Nowhere does he refer to anything that can be traced to Hindu writings such as the Vedas, or to any Buddhist writings. Nowhere is he shown preaching Hindu or Buddhist concepts such as reincarnation, karma, pantheism or nirvana. And when he is shown preaching in a synagogue in Nazareth, he is called "the carpenter's son" (Matthew 13:55), with members of his family mentioned by name. It is clear that the people of Nazareth knew him. He is not called a "traveller", and is not noted for any long absence. It is thus reasonable to believe that he spent those 18 years in and around the place where his family lived. Christian Answers explains this in more detail. Monkey Mind has more on this myth and why it's not likely to be true.
That there is any truth, or even any significance, to the backstory of The DaVinci Code.
First, let me acknowledge the obvious. The DaVinci Code is a work of fiction. My point here is not to discuss any of the events therein, but to dispute the underlying theme of the book and movie, what can be called the backstory. This theme is largely set forth in the book Holy Blood, Holy Grail by British authors Henry Lincoln, Richard Leigh and Michael Baigent, and in The Templar Revelation by Lynn Picknett and Clive Prince. According to this hypothesis, Jesus of Nazareth was married to Mary Magdalene. When he was crucified, she was pregnant. She fled to Alexandria, Egypt, where there was a significant Jewish community, and gave birth to a daughter, whom she named Sarah. When Sarah was twelve years old, she and Mary travelled to the south coast of what is now France. Sarah grew up and eventually had children of her own. Centuries later, one of her descendants married one of the Merovingian kings, who ruled part of France. This blood line, stemming from Jesus and continuing through his daughter Sarah and the Merovingian dynasty, is the real Holy Grail. In Old French, the term allegedly is sang réal, meaning "royal blood". According to this theory, Jesus did not teach his followers to worship himself as a divine incarnation, but to revere something called the "sacred feminine". Later on, at the Council of Nicaea, the early church abolished any such worship, decided to cover up the idea of Jesus having a wife and child, and also adopted the doctrine that Jesus is God. Ever since then, the church, particularly the Catholic denomination, has been trying to suppress any knowledge of Jesus being married and having a child, his teaching of the "sacred feminine", or of the bloodline descended from him through the Merovingian dynasty. In the past, some of the church's actions, such as the crusade against the Cathars, were undertaken to keep these things secret. The Cathars allegedly knew about all this, so they had to be wiped out. In The DaVinci Code, there is a woman being sought after so that she can be killed, because she is a descendant of the Merovingians and thus of Jesus. If the royal line descended from Jesus can be killed off, so the church allegedly thinks, knowledge of the secrets will be killed off, too.
There are several reasons why I don't believe the hypothesis set forth in The DaVinci Code. First of all, there is evidence that Christians were worshipping Jesus as God well before the Council of Nicaea, which convened in 325 AD. For example, Pliny the Younger, during his time as Roman governor of the province of Bythynia et Pontus, wrote a letter to Emperor Trajan in which he noted how Christians sang hymns to Christ "as to a god". He wrote this letter in 112 AD, which means that Christians were worshipping Jesus in song over 200 years before the Council of Nicaea. Second, the Council of Nicaea had nothing to do with any doctrine of a "sacred feminine" but was called to deal with a heresy called Arianism. Third, while the Catholic Church may have been uneasy about sex, generally regarding procreative sex as better than non-procreative sex, the Cathar attitude toward sex was actually more hostile. To them, sex kept the human soul trapped in material reality, which they regarded as evil. It is thus highly unlikely that the Cathars would embrace an idea that Jesus was married and therefore sexually active. Moreover, the Catholic authorities of the time would have regarded the Cathars worthy death simply for being heretics. Finally, if anyone wanted to kill off the descendants of Jesus in order to bury the knowledge that he was married and had a child might have to kill a very large number of people. This is because whether or not Jesus was their ancestor, the Merovingians today might have a lot of descendants, through a very well-known king named Charlemagne. His mother, known as Bertha Broadfoot, is thought have been a descendant of the Merovingians. If so, this would mean that Charlemagne himself, and thus his descendants, would also descend from the Merovingians. If it is true that these kings were descended from Jesus, then the number of descendants he has today, through Bertha and her son Charlemagne, would be truly enormous. For example, TopTenz lists Charlemagne as #4 among people with the most descendants. Familypedia traces the line from Charlemagne to Queen Elizabeth, among others. Eupedia lists numerous European families descended from Charlemagne, and notes several Merovingian kings as his ancestors. If all this information is correct, killing off the alleged descendants of Jesus and the Merovingians would amount to mass murder on a scale rarely seen in human history.