A UNESCO World Heritage Site, Baikal Lake in Russia at 5,387 feet is the world’s deepest, as well as being the oldest lake in the world at 25 million years old. It is 2,000 feet deeper than the Caspian Sea which is the third deepest lake in the world. Endemism occurs in the lake with half of its 60 native fish species and a freshwater seal. Baikal holds 20% of the world’s unfrozen freshwater, which amounts to around 5,662 cubic miles of crystal clear freshwater which is more than what the Great Lakes of North America holds in total volume.
The deepest river in the world is the Congo River also known as the Zaire River. The Congo River is the deepest river in the world, 3nd largest river in Africa, and the 9th largest river in the world. The Congo River runs through the Congo rainforest in the heart of the African continent, it has a length of 4700kilometers and has a width in a range of 0.5 to 10 miles (0.8-16 km).
The river’s basin covers 4,014,500 square km, which is about 13% of total African landmass. The river has been an important means of transportation for many people in Africa for many years.
The Pacific Ocean is the largest and deepest of the world ocean basins. Covering approximately 59 million square miles and containing more than half of the free water on Earth, the Pacific is by far the largest of the world's ocean basins. All of the world's continents could fit into the Pacific basin.
The Mariana Trench or Marianas Trench is the deepest part of the world's oceans. It is located in the western Pacific Ocean, an average of 200 kilometres (124 mi) to the east of the Mariana Islands, in the Western Pacific East of Philippines. It is a crescent-shaped scar in the Earth's crust, and measures about 2,550 km (1,580 mi) long and 69 km (43 mi) wide on average. It reaches a maximum-known depth of 10,994 metres (36,070 ft) (± 40 metres [130 ft]) at a small slot-shaped valley in its floor known as the Challenger Deep, at its southern end, although some unrepeated measurements place the deepest portion at 11,034 metres (36,201 ft). If Mount Everest were dropped into the trench at this point, its peak would still be over 1.6 kilometres (1 mi) underwater. In 2009, Marianas Trench was established as a United States National Monument.
In terms of depth below the surface, the Kola Superdeep Borehole SG-3 retains the world record at 12,262 meters (40,230 ft) in 1989 and still is the deepest artificial point on Earth.
Don't mind the 9-inch diameter. Instead, focus on the Kola Superdeep Borehole's unmatched 7.5-mile depth. Started in 1970 by Russian scientists on the Kola Peninsula of Russia ultimately became the deepest hole in the world—deeper than even the deepest part of the ocean—after about 20 years of digging and experimentation. The 356 Fahrenheit temperature at that depth, however, made it impossible for tools to keep going. The site has been abandoned since 2008, and the hole bolted shut so nothing can get in.