People have traveled to the deepest point in the ocean, the Challenger Deep in the Mariana Trench, nearly 11 kilometers (7 miles) down, with explorers like Jacques Piccard, Don Walsh, James Cameron, and Victor Vescovo reaching the bottom in various submersibles, facing extreme pressure and total darkness to explore this unique environment.
He reached the bottom of the Mariana Trench in the submersible vessel Deepsea Challenger, diving to a depth of 10,908 m (35,787 ft; 5,965 fathoms).
1951 – SV HMS Challenger II
The depth was beyond Challenger II's echo sounder capability to verify, so they resorted to using a taut wire with "140 lbs of scrap iron", and documented a depth of 5,899 fathoms (35,394 ft; 10,788 m).
The Mariana Trench, an adventure 11,000 metres under the sea. Discover the deepest place on the planet! There have been nearly 30 diving expeditions into the Mariana Trench since the first one in 1960, and scientists and explorers have been able to confirm that life exists even at these great depths!
Most of the ocean remains unexplored (around 80-95%) due to its immense size, extreme darkness, near-freezing temperatures, crushing pressure (over 1,000 times surface pressure in the deep), and the high cost and technological challenges of developing specialized equipment to withstand these harsh, hostile conditions. Sunlight can't penetrate far, visibility is near zero, and deep-sea life is adapted to pressure that would crush most vessels, making direct human study difficult and expensive.
We have a great deal more to learn about our ocean and what resides within it, but progress IS being made. We learn more and more each year. We continue to discover new features and creatures, clues to our past, and resources that can improve our future. But the ocean will never be fully explored.
More than 70% of our planet is ocean – and 90% of that ocean is deep sea.
However, with the proper equipment and practice, divers can descend to 1000 feet and explore for several hours. But their ascent will be extremely slow since they must make decompression pauses.
At around 300 feet, no visible light can penetrate the water at all!
The risk of DCS goes up steadily the deeper you go, and the longer you stay. For physiological reasons, it's believed you can't get DCS in max depths shallower than 20' - you can stay down indefinitely and still surface immediately fully saturated without risking DCS.
Today, over 80% of the global ocean (and 50% of the U.S. Ocean) is still unmapped, with even more unexplored. One of the biggest challenges of ocean exploration is the intense pressures in the deep ocean. In addition, zero visibility and extreme cold temperatures make it difficult to explore the vast ocean.
Without sufficient warmth you only survive hours. Without sufficient drinking water you can survive up to six or seven days in a maritime environment. Without food you can survive 40–60 days. So, those who survive more than a few hours are almost always in warm air or water.
Chris Lemons survived without oxygen for nearly 30 minutes due to a combination of his body being saturated with oxygen from the heliox gas he breathed (a helium-oxygen mix) and the near-freezing North Sea water rapidly cooling his body and brain, drastically slowing his metabolism and oxygen demand, a phenomenon often called "diving stasis," though experts still call it a miracle. His tissues held oxygen reserves, and the cold reduced his body's need for it, allowing him to last until rescue, an event documented in the film Last Breath.
However, technical divers, who undergo additional training and use specialized equipment, can explore depths beyond recreational limits, typically reaching depths of 60 meters (200 feet) or more.
Consider that while the Challenger Deep in Mariana Trench is the deepest spot currently known, other trenches come very close. Challenger Deep is about 36,000 feet, but several trenches have spots over 34,000 feet deep, including the Tonga Trench, the Philippine Trench, the Kuril-Kamchatka Trench.
Summary: 2025 is a transformative year for ocean governance, marked by three landmark events: the UN BBNJ Convention entering into force, new WTO fisheries subsidies regulations taking effect, and the adoption of a historic political declaration at the 2025 UN Ocean Conference.
What limits human exploration of deep-sea environments? The limitations of human exploration in deep-sea environments are primarily due to depth-related challenges, including increased pressure, decompression sickness risk, and orientation difficulties, which often require specialized equipment and training.
Psalm 104:25-26 – “There is the sea, vast and spacious, teeming with creatures beyond number-living things both large and small. There the ships go to and fro, and Leviathan, which you formed to frolic there.” Psalm 95:5 – “The sea is his, for he made it, and his hands formed the dry land.”
Many got slightly disoriented, but thankfully without any incident. That is one of the main reasons why Stephen decided to do a VWT dive down to the bottom and wait there for Alessia's exit, to optimize her level of safety and be ready to guide her to the ascent dive line if necessary.
The 120 Rule in scuba diving is a simple guideline for estimating your No Decompression Limit (NDL) for recreational air dives: 120 minus your depth in feet equals your maximum bottom time in minutes (e.g., 120 - 60ft = 60 min). It helps manage nitrogen absorption, keeping dives safer by suggesting shorter times at greater depths to avoid decompression sickness, but it's a conservative estimate, best for shallower dives (under 100 ft), and doesn't replace dive computers or tables for complex dives (like those using Nitrox).
The TLC was predicted to be reduced to RV at around 30 meters; below this depth, it was believed that total lung collapse would occur.
Distribution of countries according to their share of the Earth's surface. The largest countries in terms of area are Russia (3.35%), Canada (1.96%) and China (1.88%). Together they occupy about 7.2% of the Earth's surface.
More than 70% of Earth's surface is covered by ocean, yet we have mapped less than 25% of the seafloor in high resolution. Over 95% of Earth's habitable space exists beneath the ocean's surface. That means nearly all of life's potential environments remain unexplored.
Despite the importance of visual observation in the ocean, we have imaged a minuscule fraction of the deep seafloor. Sixty-six percent of the entire planet is deep ocean (≥200 m), and our data show that we have visually observed less than 0.001%, a total area approximately a tenth of the size of Belgium.