Collecting and Visualizing Deep-Sea Data

What Are Data and Data Visualization?

Data is information that we collect about the world. In the context of NOAA Ocean Exploration, it is the information that we collect about the deep sea. Data can be both quantitative and qualitative. Quantitative data refers to information that is numeric: it is anything that can be counted or measured. In the deep sea, quantitative data types can include things like the number of fish seen or the area covered by deep-sea corals. Qualitative data is more descriptive and refers to things that can be observed but not necessarily measured numerically. For example, in the deep sea, we may collect qualitative data about the behavior of a particular organism.

Data visualization is the representation of data through the use of graphics such as charts, plots, pictures, or graphs compared to text alone.

Images and graphics are effective for all kinds of storytelling, especially when the story is complicated, which is often the case in science. Data visualization can also allow us to see trends and patterns in the data that we might not see if we were just looking at numbers alone. Scientific visuals can be essential for analyzing data, communicating results, and for making new discoveries.

Examples of Different Data Visualizations

Example of Acoustic Doppler Current Profiler (ADCP) velocities with depth. This color panel plot shows three panels with horizontal velocities in the east-west (E/W) direction (top panel), north-south (N/S) direction (second panel) and signal return (bottom panel). Time increases from left to right as the ship transits to the northwest (same data as the vector plot, above). The vertical axis is depth in meters.

Remotely operated vehicle (ROV) track and the measured parameters an ocean exploration dive: (top left) depth (meters), (top right) temperature (°C), (bottom left) pH, and (bottom right) dissolved carbon dioxide (pCO₂; in microatmospheres or µatm). Blue and red dots indicate the start and end of the dive. The ROV first dove to around 150 meters (492 feet) at the base of the reef (blue dot in the top left panel), slowly climbed the reef wall and then moved around on top of the reef. Spatially the ROV covered about 300 meters (984 feet) in the west-east direction and less than 100 meters (328 feet) north-south over a period of approximately 3 hours.

This is an example of what the deep-scattering layer looks like when graphed as an echogram, which is a plot of active acoustic data. Warmer colors indicate more backscatter, meaning that more (or stronger) echoes were received back from the organisms at that depth. The red line indicates the remotely operated vehicle trajectory as it performs transects throughout the layer. The scale on the left represents depth in meters.

Deep Sea Coral Data Portal digital map showing known locations of corals (circles) and sponges (triangles). Coral and sponge location records are tagged with metadata and many have associated photographs available as well. Note that the map does not yet show areas in which researchers have searched and found no coral.

Methane hydrate is stable to the left of the purple curve on this temperature-depth plot. Each 100-meter (328-foot) increase in water depth corresponds to a pressure increase of approximately 10 megapascals (98 atmospheres). The blue curve shows the ocean temperatures measured by the conductivity-temperature-depth (CTD) sensor on remotely operated vehicle Deep Discoverer. The sediment temperatures are estimated based on a study that examined nearby well data. Gas hydrate is stable at the seafloor, in the shallow sediments, and from the seafloor to approximately 600 meters (1,967 feet) depth in the water column. Such conditions are typical for the deep ocean, but the Gulf of Mexico leaks such large volumes of gas that near-seafloor gas hydrate is more common there than in most locations.

Example of Acoustic Doppler Current Profiler (ADCP) velocities with depth. This color panel plot shows three panels with horizontal velocities in the east-west (E/W) direction (top panel), north-south (N/S) direction (second panel) and signal return (bottom panel). Time increases from left to right as the ship transits to the northwest (same data as the vector plot, above). The vertical axis is depth in meters. Image courtesy of NOAA Ocean Exploration. Download largest version (jpg, 805 KB). Learn more

Remotely operated vehicle (ROV) track and the measured parameters from an ocean exploration dive: (top left) depth (meters), (top right) temperature (°C), (bottom left) pH, and (bottom right) dissolved carbon dioxide (pCO₂; in microatmospheres or µatm). Blue and red dots indicate the start and end of the dive. The ROV first dove to around 150 meters (492 feet) at the base of the reef (blue dot in the top left panel), slowly climbed the reef wall and then moved around on top of the reef. Spatially the ROV covered about 300 meters (984 feet) in the west-east direction and less than 100 meters (328 feet) north-south over a period of approximately 3 hours. Image courtesy of Undersea Vehicles Program, University of North Carolina Wilmington, Cuba’s Twilight Zone Reefs and Their Regional Connectivity. Download largest version (jpg, 343 KB). Learn more

Composite image showing the original Sandwell and Smith satellite-derived bathymetry data at the bottom, with NOAA Ship Okeanos Explorer EM302 multibeam bathymetry transit data further revealing this unnamed seamount overlain on top. The middle image is a top-down view of the bathymetry data showing the seamount, and the graph in the upper left corner shows the vertical profile of the seamount’s height relative to the seafloor. The map on the upper right shows the bathymetry of the Hawaiian Archipelago with the Papahānaumokuākea Marine National Monument boundary in white, and the location of the seamount circled in red. Image courtesy of NOAA Ocean Exploration, 2015 Hohonu Moana. Download largest version (jpg, 1.4 MB). Learn more

This is an example of what the deep-scattering layer looks like when graphed as an echogram, which is a plot of active acoustic data. Warmer colors indicate more backscatter, meaning that more (or stronger) echoes were received back from the organisms at that depth. The red line indicates the remotely operated vehicle trajectory as it performs transects throughout the layer. The scale on the left represents depth in meters. Image courtesy of NOAA Ocean Exploration. Download largest version (jpg, 584 KB). Learn more

Deep Sea Coral Data Portal digital map showing known locations of corals (circles) and sponges (triangles). Coral and sponge location records are tagged with metadata and many have associated photographs available as well. Note that the map does not yet show areas in which researchers have searched and found no coral. Image courtesy of the NOAA Deep Sea Coral Research and Technology Program. Download largest version (jpg, 3.1 MB). Learn more

Methane hydrate is stable to the left of the purple curve on this temperature-depth plot. Each 100-meter (328-foot) increase in water depth corresponds to a pressure increase of approximately 10 megapascals (98 atmospheres). The blue curve shows the ocean temperatures measured by the conductivity-temperature-depth (CTD) sensor on remotely operated vehicle Deep Discoverer. The sediment temperatures are estimated based on a study that examined nearby well data. Gas hydrate is stable at the seafloor, in the shallow sediments, and from the seafloor to approximately 600 meters (1,967 feet) depth in the water column. Such conditions are typical for the deep ocean, but the Gulf of Mexico leaks such large volumes of gas that near-seafloor gas hydrate is more common there than in most locations. Diagram provided by C. Ruppel, U.S. Geological Survey. Download largest version (jpg, 1.9 MB). Learn more

What Kind of Data Do Ocean Explorers Collect?

Mapping Data

Remotely Operated Vehicle Data

Environmental Sensor Data

Mapping Data Types

Two types of data are often collected when mapping: bathymetry and backscatter data. Both of these use sonar—devices that use sound waves to detect objects. Bathymetry is the measurement of the depth of the seafloor, similar to elevation on land. A special instrument called a multibeam echosounder is mounted on the bottom of a ship. The multibeam echosounder emits sound into the water, and that sound hits the seafloor and “echoes” back to the ship. We are able to measure how long it takes the sound to travel back to the ship, and can then calculate the depth of the seafloor using the known speed of sound through water.

Slide the arrow back and forth to compare bathymetry data and backscatter data of Michael Seamount. Images courtesy of NOAA Ocean Exploration, 2021 North Atlantic Stepping Stones.

This information can be used to create maps that are important tools for navigating the ocean. The same instrument, along with others mounted on the ship, also collects backscatter data. Backscatter data can determine the relative hardness of the seafloor or other objects that the signal encounters in the water column. Rather than measure the time for an echo to return to the ship (like with bathymetry), backscatter is computed by measuring how loud the sound return is compared to the original sound emitted. When an area of the seafloor has sand or soft sediment, much of the sound will be absorbed, and the return to the sonar will be low.

When we are mapping over hard substrate, such as rock or coral reef, the backscatter return will be greater because the sound is bouncing off the hard substrate and less sound is absorbed into the sediment. Backscatter can also tell us if there are organisms or other objects located in the water column. We can identify the presence of large organisms, like big fish or whales, or whether there are groups of smaller organisms such as plankton or schools of small fish. Backscatter can also be used to detect bubbles in the water column, which can help us identify the location of seeps—areas on the ocean floor where gases percolate through underlying rock and sediment layers and emerge on the ocean bottom.

Rasters are pixelated and made up with individual cells. The resolution of a raster is the height and width of that particular cell. In the case of bathymetry data, each cell would contain the depth of the seafloor within that area. *Images adapted from ESRI.* Download largest version (jpg, 471 KB).

Using special software, we are able to make these data into grids, called rasters. These are matrices of pixels organized into rows and columns where each cell contains a value representing information. In this case, the rows and columns represent the location on the Earth (such as latitude and longitude), and each cell would be defined as depth (bathymetry) or intensity (backscatter) of the seafloor or other objects. Another way that data can be made available for use is through geographic information systems (GIS). These systems store geographic information in layers and use specialized software to create, store, analyze, and visualize spatial information.

Remotely Operated Vehicle Data Types

Remotely operated vehicles (ROVs) are commonly used to collect video and imagery of the water column and seafloor. The video and imagery collected by the ROVs are often the first images of an area ever collected and are important for making discoveries about the deep sea.

Okeanosaster hohonui represents a new genus and a new species and has a different structure than other sea stars in the family Goniasteridae seen at similar depths. It was named to honor NOAA Ship Okeanos Explorer. “Hohonu,” the Hawaiian word for deep, refers to the great depth at which the sea star was seen. The new sea star, seen here in the Musicians Seamounts in Papahānaumokuākea Marine National Monument Monument, was documented at depths ranging from 1,743 to 3,304 meters (1.1 to 2.1 miles).

This comb jelly, or ctenophore, was first seen during a 2015 dive with the NOAA Ocean Exploration team. This marks the first time NOAA scientists exclusively used high-definition video to describe and annotate a new creature.

While exploring “Ridge” Seamount during the 2017 Laulima O Ka Moana: Exploring Deep Monument Waters Around Johnston Atoll expedition, remotely operated vehicle Deep Discoverer encountered this alien-like community composed almost exclusively of glass sponges that were uniformly oriented with the direction of the current. Amongst these sponges was the now newly described and named “E.T. sponge.”

Casper, the ghost-like octopod, became a social media celebrity after it was seen for the first time during a dive in the deep waters of Hawai‘i. Scientists believe it represents a new species, and possibly a new genus, of octopod.

Okeanosaster hohonui represents a new genus and a new species and has a different structure than other sea stars in the family Goniasteridae seen at similar depths. It was named to honor NOAA Ship Okeanos Explorer. “Hohonu,” the Hawaiian word for deep, refers to the great depth at which the sea star was seen. The new sea star, seen here in the Musicians Seamounts in Papahānaumokuākea Marine National Monument Monument, was documented at depths ranging from 1,743 to 3,304 meters (1.1 to 2.1 miles). Image courtesy of NOAA Ocean Exploration, Deep-Sea Symphony 2017. Download largest version (jpg, 1.1 MB). Learn more

This comb jelly, or ctenophore, was first seen during a 2015 dive with the NOAA Ocean Exploration team. This marks the first time NOAA scientists exclusively used high-definition video to describe and annotate a new creature. Image courtesy of NOAA Ocean Exploration, Exploring Puerto Rico’s Seamounts, Trenches, and Troughs. Download largest version (jpg, 1.3 MB). Learn more

While exploring “Ridge” Seamount during the 2017 Laulima O Ka Moana: Exploring Deep Monument Waters Around Johnston Atoll expedition, remotely operated vehicle Deep Discoverer encountered this alien-like community composed almost exclusively of glass sponges that were uniformly oriented with the direction of the current. Amongst these sponges was the now newly described and named “E.T. sponge.” Image courtest of NOAA Ocean Exploration, 2017 Laulima O Ka Moana. Download largest version of video (jpg, 40.3 MB). Learn more

Casper, the ghost-like octopod, became a social media celebrity after it was seen for the first time during a dive in the deep waters of Hawai‘i. Scientists believe it represents a new species, and possibly a new genus, of octopod. Image courtesy courtesy of NOAA Ocean Exploration, 2016 Hohonu Moana. Download largest version (jpg, 906 KB). Learn more

Underwater video collected during ROV dives can be used to describe geological, physical, chemical, and biological processes and can also be used to document possible archaeological sites.

After a first attempt to find World War II-era oil tanker SS Bloody Marsh during Windows to the Deep 2019, NOAA Ocean Exploration returned to the area where the ship was lost and located what is likely its remains during Windows to the Deep 2021. Video courtesy of NOAA Ocean Exploration, Windows to the Deep 2021. Download largest version (mp4, 95.4 MB).

In the case of NOAA Ocean Exploration, two ROVs continuously film and transmit high-resolution video data during a dive. ROV Deep Discoverer is also equipped with two lasers, spaced 10 centimeters (4 inches) apart, which can be used to measure the lengths of organisms or objects.

During ROV dives, many ocean exploration organizations will livestream the video back to shore, so anyone can watch the dive, right from their own home! The technology used to accomplish this is called telepresence. Scientists from around the world tune into the ROV dives from shore and make annotations of imagery and video that are collected. This means they mark a timestamp in the live video and enter information about what is being seen, such as organisms or geological features of interest, in order to keep a record of scientific observations. These dive annotations also provide a wealth of data about the deep sea that can also be visualized.

The red lasers (red dots in photo) are 10 centimeters apart, which helps scientists measure the mussels of varying sizes in this chemosynthentic community. *Image courtesy of NOAA Ocean Exploration, Northeast U.S. Canyons Expedition 2013.* Download largest version (jpg, 1.6 MB).

This graphic illustrates the process that NOAA Ocean Exploration uses to deliver data from sensors on NOAA Ship Okeanos Explorer back to shore. — This graphic illustrates the process that NOAA Ocean Exploration uses to deliver data from sensors on NOAA Ship *Okeanos Explorer* back to shore. *Image courtesy of NOAA Ocean Exploration.* Download largest version (jpg, 74 KB).

The ROVs also contain instrumentation used for georeferencing, meaning that the geographic coordinates of the ROVs can be determined as they survey the deep sea. Because of this, we also have the latitude and longitude for each of the annotations that are made. We can look at an organism of interest and then plot its location on a map.

Remotely operated vehicles are often fitted with other specialized equipment in addition to lights and cameras, including manipulator arms and suction samplers, which are used to collect biological and geological specimens. These specimens can provide a general representation of the biological and geological information of the site we explore. When we collect biological specimens, NOAA Ocean Exploration sends them to the Smithsonian Institution’s National Museum of Natural History. Scientists then study them for a variety of purposes, ranging from determining if they represent a species new to science to better understanding the relationships between organisms. Geological samples, specifically rock samples, are collected to understand the geological history of a location. For example, the geology of the deep sea can reveal information about how that section of the ocean floor was formed.

The manipulator arm of remotely operated vehicle (ROV) Deep Discoverer reaches out to collect the first sample of the 2023 Shakedown + EXPRESS West Coast Exploration expedition at a depth of 3,952 meters (2.46 miles). While the focus of this dive was on “shaking down” the ROVs, the team was happy to collect this zoanthid growing on a dead sponge stalk. — The manipulator arm of remotely operated vehicle (ROV) *Deep Discoverer* reaches out to collect the first sample of the 2023 Shakedown + EXPRESS West Coast Exploration expedition at a depth of 3,952 meters (2.46 miles). While the focus of this dive was on “shaking down” the ROVs, the team was happy to collect this zoanthid growing on a dead sponge stalk. *Image courtesy of NOAA Ocean Exploration, 2023 Shakedown + EXPRESS West Coast Exploration.* Download largest version (jpg, 900 KB).

Environmental Sensor Data Types

There are also a number of specific electrical sensors that can measure the environmental conditions of the water column. For example, scientists often use a group of sensors called a CTD, which stands for conductivity, temperature, and depth, to collect water column information.

The CTD (standing for "conductivity, temperature, and depth") is a vital instrument when conducting scientific research on ships. Video courtesy of Caitlin Bailey, GFOE, The Hidden Ocean 2016: Chukchi Borderlands, Oceaneering-DSSI. Download largest version (mp4, 41.2 MB).

A CTD device’s function is to measure how the conductivity and temperature of the water column change with depth. For CTDs mounted on ROVs, as the pilots guide the ROVs down to the seafloor, the CTD sensors constantly measure the environmental properties of the water column as compared to depth. For example, we can see that the water temperature is generally warmer at the surface and gets much colder the deeper an ROV descends. Conductivity is a measure of how well a solution conducts electricity, and it is directly related to salinity, or the “saltiness” of the water. The depth value is derived from the pressure measured by one of the electrical sensors.

Environmental sensor data is visualized through a line graph. On the y-axis we have our independent variable, which is depth. The x-axis contains the dependent variable, which is either temperature, conductivity, salinity, or dissolved oxygen. These variables are dependent on depth. Below is a graph of how CTD data are normally visualized.

These three line graphs show the temperature, salinity, and concentration as derived from the environmental sensors on the CTD rosette. The data pictured here was collected from one CTD rosette cast conducted during the Windows to the Deep 2019 expedition. During the cast, the temperature got much colder the deeper down the CTD rosette went. The salinity graph is showing a similar trend—the water is saltier at the surface because water at the surface evaporates, leaving the salts behind. For the oxygen graph, a greater number means there is more dissolved oxygen in the water. In this figure, we can see the oxygen minimum zone is about 800 meters (2,624 feet). Once the CTD rosette passes out of this zone, the oxygen levels spike again at around 1,000 meters (3,280 feet). *Image courtesy of NOAA Ocean Exploration, Windows to the Deep 2019.* Download largest version (jpg, 593 KB).

Ocean explorers work to combine the different data types described in this article to tell a story about an area of the deep sea that we have explored. By combining all this data and visualizing it, we can understand things like why organisms live in that particular area of the ocean. Is it due to the environmental conditions determined using the CTD sensors? Is it the way the seafloor is shaped, which we can picture using mapping data? Is it all of the above? Data visualization also provides a way to tell other scientists what data we collected so they can build upon it to further our understanding of the deep sea. Data visualization can also provide the public with a better appreciation of the deep sea. Just like books, each data type or point of data can be thought of as a word or a sentence. When put together, they reveal a fuller picture of one of the most unexplored but important ecosystems in our ocean.

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Published June 12, 2023