Ocean exploration vs. space exploration is mostly a story of money and difficulty. NASA received about $24.4 billion from Congress for fiscal year 2026. NOAA’s ocean exploration office, by contrast, runs on roughly $46 million a year. Yet the ocean covers about 71% of Earth, and as of April 2026 only 28.7% of the seafloor has been mapped in high detail.
So the deep sea is not ignored because it is boring. It is harder to reach in some ways than orbit, and it gets a tiny share of public funding. Below is how the two fields compare on budgets, people, technology and results, with figures checked as of October 2026. For more explainers like this one, see our science and technology guides.
How much of the ocean has been explored
The answer depends on what “explored” means. Satellites have mapped the whole seafloor, but only at a coarse resolution. Those maps miss most hills, canyons and wrecks. High-resolution mapping needs ships with multibeam sonar, and that work is slow.
The international Seabed 2030 project reported in April 2026 that 28.7% of the global seafloor is now mapped to modern standards. That is about 104 million square kilometers. The project added roughly 5 million square kilometers in a single year, up from 27.3% in June 2025.
Seeing the seafloor is another matter. According to NOAA’s page on how much of the ocean has been explored, people have directly observed less than 0.001% of the deep-ocean seafloor. That is an area about the size of Rhode Island. NOAA also notes that about 56% of the seafloor in US waters is mapped to modern standards.
| Measure | Figure | Source and date |
|---|---|---|
| Global seafloor mapped in high resolution | 28.7% | Seabed 2030, April 2026 |
| US seafloor mapped to modern standards | About 56% | NOAA Ocean Exploration, 2026 |
| Deep seafloor seen by humans or cameras | Less than 0.001% | NOAA Ocean Exploration, 2026 |
| Ocean species still undescribed | Roughly two-thirds | NOAA estimate |
Compare that with space. Orbiters have mapped the Moon and Mars in more detail than most of our own seafloor. That gap is the usual starting point for this debate.
Budgets compared: NASA vs. NOAA Ocean Exploration
The funding gap is very large. Congress passed the fiscal 2026 Commerce, Justice and Science bill in January 2026. The Senate Appropriations Committee summary lists $24.4 billion for NASA, including $7.25 billion for science.
NOAA’s Office of Ocean Exploration and Research had $46 million enacted for fiscal 2024. In NOAA’s fiscal 2026 budget justification, the program again appears at $46 million, with a proposal to move it to the National Ocean Service. NOAA calls it the only federal organization dedicated to ocean exploration.
| Program | Annual funding | Year |
|---|---|---|
| NASA (whole agency) | About $24.4 billion | FY2026 enacted |
| NASA science missions | $7.25 billion | FY2026 enacted |
| NOAA Ocean Exploration and Research | $46 million | FY2024 enacted; same level in the FY2026 request |
On those numbers, NASA’s budget is more than 500 times larger. That said, the comparison is not perfectly fair. Ocean science money also flows through the National Science Foundation, the Navy and other parts of NOAA. Private groups such as the Schmidt Ocean Institute add their own ships. Still, no ocean agency has anything close to NASA’s scale.
Why the deep sea is so hard to explore
Space has one big enemy: getting off the ground. The deep sea has several problems at once, and they never let up.
- Pressure. Water pressure rises by about one atmosphere every 10 meters, according to NOAA. The Challenger Deep is nearly 11,000 meters down, so pressure there is more than 1,000 times the pressure at the surface. A spacecraft only has to hold one atmosphere against a vacuum.
- Darkness. Sunlight fades out at roughly 200 meters. Below that, every image needs powerful lights, and even then a camera sees only a few meters through the water.
- Communication. Radio waves barely travel through seawater. So subs rely on slow acoustic signals or on a physical cable to the ship. A rover on Mars can send pictures home by radio; a free-swimming robot a few kilometers deep often cannot.
- Navigation. GPS does not work underwater either. Vehicles track their position with sound beacons and onboard sensors, which drift over time.
- Corrosion and cold. Saltwater eats metal and electronics, and deep water stays just above freezing.
In practice, this means every deep dive needs a large ship, a skilled crew and good weather. Ship time is expensive, which limits how much ground any one expedition covers.
Did we stop exploring the ocean?
No. The idea comes from a gap in headlines, not a gap in work. After the 1960 Trieste dive to the Challenger Deep, no one returned there with a crew for 52 years. However, exploration moved to robots, sonar ships and research submersibles such as Alvin.
That work keeps producing results. In 1977, scientists in Alvin found hydrothermal vents near the Galapagos, with whole ecosystems living off chemical energy instead of sunlight. Our archive covered later work on how submarine volcanoes reveal their formation histories, the kind of research that research vessels now do routinely.
The real limit is funding and ship time. Crewed dives are rare because robots are cheaper and safer. So ocean exploration rarely produces a single televised moment like a rocket launch, even when the science is steady.
How many people have been to the deepest point vs. to space
This is the comparison people quote most, and it holds up. By the most widely used tally, about 27 people have descended to the Challenger Deep in the Mariana Trench. Most of those dives happened between 2019 and 2022, many of them in Victor Vescovo’s submersible Limiting Factor. No new crewed descents have been widely reported since July 2022.
Space has far more visitors. Counting everyone who has crossed the 100-kilometer Karman line, roughly 750 people from more than 50 countries have flown to space as of late 2026. Twelve people have walked on the Moon. In April 2026, NASA’s Artemis II crew flew around the Moon and splashed down off San Diego on April 10.
For more than half a century, more people had walked on the Moon (12) than had reached the Challenger Deep (2). Even now, space travelers outnumber deep-trench visitors by more than 25 to 1.
What each field has given us
Both fields pay off, but in different ways.
From space exploration
- Weather and climate satellites that feed daily forecasts and hurricane warnings.
- GPS-based navigation, which also guides ships and fishing fleets.
- Commercial products tracked by NASA’s Spinoff program, such as memory foam, infrared ear thermometers and water purification systems.
- Advances in physics and computing. For example, our archive covered a 2018 supercomputer simulation of merging supermassive black holes, work that leans on the same modeling methods used in climate and ocean science.
From ocean exploration
- Seafloor maps that make shipping, undersea cables and tsunami forecasts safer.
- New species and compounds. Scientists describe almost 2,000 new ocean species each year, according to NOAA, and some marine compounds have become medicines.
- A better picture of climate, because the ocean stores most of the extra heat trapped by greenhouse gases.
- Insight into the origin of life, since vent ecosystems show that life can run without sunlight.
Interestingly, the two fields also help each other. Satellites measure sea level and map the seafloor roughly from orbit. Meanwhile, NASA studies deep-sea vents to understand where life might exist on ocean moons such as Europa and Enceladus.
Current missions to follow
On the ocean side, NOAA Ship Okeanos Explorer has a full 2026 field season. It began with a mapping test off Hawaii in spring, then moved to two deep-sea expeditions around American Samoa from August through October 2026. Those dives stream live video daily, and NOAA makes the data public.
Also, the Schmidt Ocean Institute’s ship Falkor (too) runs expeditions year-round, and its 2026 voyages have already reported dozens of new species. Seabed 2030 keeps adding mapped areas, with the goal of a complete high-resolution map by 2030.
On the space side, NASA’s Artemis program is preparing the next crewed lunar missions after the Artemis II flyby. Robotic science missions continue across the solar system, funded under the $7.25 billion science budget for 2026.
Frequently asked questions
Why is ocean exploration important?
The ocean drives weather, absorbs heat and carbon, and feeds billions of people. Better maps also make shipping, cables and tsunami warnings safer. Since most species there are still unknown, each expedition can find new life and new compounds.
How much of the ocean has been mapped?
As of April 2026, Seabed 2030 reports that 28.7% of the global seafloor is mapped in high resolution. Humans have directly seen less than 0.001% of the deep seafloor, according to NOAA.
Is ocean exploration harder than space exploration?
In several ways, yes. Deep-sea vehicles face more than 1,000 atmospheres of pressure, total darkness and no radio contact. Space has vacuum and radiation, but radio links work across millions of miles.
Why does NASA get more money than ocean exploration?
NASA carries large crewed programs, rockets and national prestige, so Congress funds it at about $24.4 billion for 2026. Ocean exploration is a small office within NOAA at about $46 million, though other agencies also fund ocean science.
