Mother Ocean Day is Saturday, May 9, so here’s a few facts about our waters.
About 71% of the Earth’s surface is water-covered, and the oceans hold about 96.5% of all Earth’s water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers, and even in you and your dog. Water is never sitting still.
This image above shows blue spheres representing relative amounts of Earth’s water in comparison to the size of the Earth. Each sphere represents volume. They show that in comparison to the volume of the globe, the amount of water on the planet is very small.
Oceans account for only a thin film of water on the surface.
The largest sphere represents all of Earth’s water. Its diameter is about 860 miles (the distance from Salt Lake City to Topeka, Kansas) and has a volume of about 332,500,000 cubic miles. If all of the world’s water was poured on the contiguous United States, it would cover the land to a depth of about 107 miles.
The heart of Earth
The ocean influences and regulates Earth’s climate, acting like the planet’s ‘heart.’
Ocean currents circulate vital heat and moisture around the globe, similar to the human circulatory system. Physical oceanic processes like the El Niño-Southern Oscillation in the Pacific Ocean basin and the Gulf Stream current in the Atlantic can influence climate worldwide. Just like our hearts must be monitored and cared for to ensure long-term health, U.S. Geological Survey studies our oceans to better understand these processes and how they influence our climate. This knowledge is critical for monitoring and predicting how our ocean-climate system is shifting, affecting both people and ecosystems in our changing world.
Salt of the Earth
If the salt in the ocean could be removed and spread evenly over the Earth’s land surface, it would form a layer more than 500 feet thick.
Mapping the seafloor
With oceans covering 71% of the Earth’s surface, the marine ecosystem is the largest and most abundant in the world. But most of the ocean is permanently dark and incredibly difficult to observe. As of 2022, the National Oceanic and Atmospheric Administration had mapped slightly more than 28.7% of the seafloor in great detail (as of April), and even less has been explored with underwater cameras or submersibles. Mapping the seafloor is the first step in exploring the unknown depths of our global ocean.
Explorers have seen less than 0.001% of the deep ocean seafloor — that’s roughly the size of Rhode Island. Since more than 90% of the ocean is deep ocean (deeper than 656 feet), a very large majority of the ocean remains to be explored.
What is sonar?
Sonar stands for sound navigation and ranging. There are two main types of sonar: active sonar and passive sonar. Active sonar systems emit a pulse of sound into the water, which then bounces off the seafloor, creating an echo. Seafloor depth is calculable using the time difference between creating a sound and receiving its echo.
NOAA Ocean Exploration is an organization dedicated to exploring the deep ocean and filling the gaps in our understanding of the world’s deep waters.
Scientists and governments around the world recognize the importance of making a high-resolution global map of the seafloor. An international collaboration called the Nippon Foundation-GEBCO Seabed 2030 Project aims to produce a high-resolution global map of the seafloor by 2030. It has been calculated that it would take one ship nearly 1,000 years to map the entire ocean at all water depths.
Why is it important?
NOAA scientists say a global seafloor map will benefit us all. We will be able to accurately view the entirety of the Earth’s surface for the first time. Having this data layer will improve global prediction models related to weather and climate, tsunami impact zones and sea-level rise. Countries will be able to prioritize conservation efforts to improve fish stocks and coral reefs. Seeing the seafloor with such clarity will reveal more information than we can imagine.
Seafloor maps can provide information about geological features and potential habitats, but they can’t identify species on the seafloor or in the water column or provide information about how organisms interact with each other and their environments. Scientists estimate there may be between 700,000 and 1 million species in the ocean (mostly animals and excluding most microorganisms, of which there are millions).
The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred miles southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 7 miles deep. It is named after the HMS Challenger, whose crew first sounded the depths of the trench in 1875.
According to National Geographic, if you were to put Mount Everest at the bottom of the Mariana Trench, its peak would still sit around 7,000 feet below sea level.
Even at the very bottom, life exists. In 2005, tiny single-celled organisms called foraminifera, a type of plankton, were discovered in the Challenger Deep.
Sources: NOAA, International Fund for Animal Welfare, Unworldoceansday.org, USGS