The deepest ocean point on earth's surface. The Mariana Trench is so huge and deep that it can comfortably accommodate mount Everest if flipped and dipped there.
The pressure at the bottom of the trench is so enormous that normal submarines would simply be crushed at the bottom. Very specialized and expensive submarines have been designed to explore the trench, which we yet have to learn about.
The Mariana Trench is of particular interest to scientists because of the very harsh conditions down there. Evidence of life has been found at the deepest point, which puzzles the scientists due to the complete absence of sunlight.
The mega frozen continent at the south pole is among the harshest places on earth. It is the driest, coldest, and windiest continent on the planet.
Antarctica contains 90% of the ice on earth and 70% of the world’s fresh water supply. Despite all the expeditions and international scientific bases, only 30% of Antarctica has been actually visited due to extreme weather conditions there.
The largest rainforest by far and home to the second-longest river in the world. Despite being located in the heart of South America and surrounded by civilization from all sides, more than 50% of the Amazon forest is virtually untouched. The reason is that it is very much inhabitable and especially in canopy areas where the ground is in permanent darkness due to the thickness of the trees. Another reason is that large portions of the Amazon are considered off-limits to most people because of nature protection.
The world's oldest desert and among the driest places on earth. Namib South Desert is an extreme place just like most items on this list. It is estimated that 90% of the desert is still unexplored. It is easy to understand once you know that the majority of the place is just sand dunes.
Northeast Siberia, Yakutia
Boosting extremely low temperatures in winter and home to the world's coldest large city, Yakutsk. The weird part of Yakutia is that in the summer the region is acceptably warm but still large portions of the region are unexplored.
Greenland is the least populated autonomous country in the world (0.028 people for each KM) and for good reason. The weather conditions are extreme in the majority of the country, especially in the northern islands. This led to more than 30% of the country not being explored.
Northern Patagonia, Chile
Chile is home to the wildest landscapes in South America and the world. The region boasts tens of thousands of miles of explored forests, peaks, rivers, and lakes. It is also home to one of the largest masses of ice found outside the north and south poles.
It is the highest unclimbed mountain in the world and it is located in Bhutan. Several attempts have been made to reach its summit but all failed due to extreme weather conditions.
In 2003, climbing the mountain has been banned by the Bhutan government because it is believed to be sacred and must remain untouched.
A remote mountain in Pakistan that is very difficult to access geographically. Very few attempts have been made to reach its summit but without success.
Muchu Chhish is the highest unclimbed permissible mountain in the world at 7,453 meters. Gangkhar Puensum (7,570m) is higher but it is not available for climbing anymore.
North Sentinel Island
The North Sentinel Island is a small island that lies in the Bay of Bengal between India and Thailand.
The island is not an unsafe place by itself, but it is rather dangerous to visit because it is the home of around 200 indigenous tribal people who never had any contact with the outside world and continue to live in the most primitive ways imaginable.
In 2006, two fishermen were killed by the native residents after their boat accidentally drifted to the shores of the island.
The Sentinelese apparently view any outsider as a threat and will treat them with violence. Modern humans can choose to invade the island if they wanted to, but we decided to leave these people alone so visiting the island is not an option at the moment.