Bathymetry, Oceanography, and the Seabed 2030 Project

Mapping the Earth means mapping the ocean. So far, only 24.9% of the ocean has been mapped. This means that our picture of the world is incomplete. We are missing vital knowledge of the planet we inhabit.

Detailed maps of the ocean are necessary for disaster preparedness, in the event of tsunamis and coastal floods. These maps are needed for navigation and maritime safety, climate research, resource extraction, marine construction, and ecosystem conservation.

Marie Tharp was a geologist and cartographer at Lamont-Doherty who helped to create the very first maps of the world's ocean floor. Tharp was one of many women who broke into male-dominated fields following the draft for World War II. As early as 1952, Tharp discovered the rift valley in the Mid-Atlantic Ridge, which paved the way for the scientific acceptance of plate tectonics and continental drift. (Tharp's longtime colleague Bruce Heezen infamously dismissed her findings on seafloor spreading as "girl talk".)

Throughout the 1950s, she and Heezen worked to make the first complete maps of the Atlantic Ocean. By 1977, with help from artist Heinrich Berann, they had finished a map of the entire ocean. Tharp's maps were remarkably accurate given the paucity of data at the time. Her interpolations still hold up compared with more recent bathymetric projections. In her day, Tharp received little credit for her geographic findings, but by 1997 the Library of Congress named her as one of the greatest cartographers of the 20th century.

Land is to topography as sea is to bathymetry. The Earth's geographic terrain doesn't end once you reach a coastline. It continues on, getting deeper and deeper, eventually forming ridges, trenches, and other seafloor features.

Depth is relevant to the study of marine habitats, in addition to plate tectonics (i.e. seafloor spreading). From bathymetry data, we can glean other characteristics about the ocean's floor such as rugosity and slope.

There are many obstacles to reaching the seafloor: poor visibility, extreme water pressure and temperatures, and of course the sheer depth and distance from the surface. Scientists depend heavily on technology, such as USVs (uncrewed surface vessels), for studying the ocean. For bathymetry, the main instrument of choice is sonar.

Research vessels use sonar by sending pulses of sound into the water to see how long they take to return. The depth of the water is determined based on the travel time of the pulse and the measured speed of sound. Sonar is also used to find out the composition of the seafloor (via backscatter).

The main types of sonar are single beam and multibeam sonar. Single beam sonar is appropriate for smaller vessels that go in shallower water. Multibeam sonar is preferred when exploring large bodies of water with complex seafloor topography. While single beam sonar features a straightforward design, multibeam requires specialized training to operate.

Multibeam sonar typically includes motion sensors that correct for unintended sensor motion. Still, the advanced technology used for bathymetry remains vulnerable to errors. Waves, bubbles, and objects in the sea (such as fish), can all result in aberrant sonar data. Bathymetric data cleaning has yet to be fully automated, so scientists have to process the data manually.

In 2017, only 6% of the ocean had been adequately mapped, and the United Nations' Sustainable Development Goal for the ocean seemed out of reach. A glaring insufficiency in bathymetric data meant that ocean conservation efforts were stalling. The Nippon Foundation and GEBCO launched Seabed 2030, a global movement that aims to complete a map of the ocean in high resolution by 2030. 

Seabed 2030 targets four "priority" regions, joining people from around the globe and all sectors of the maritime community to achieve their goal. Collaboration and teamwork are a requirement in accomplishing such a feat. Countries around the world need to work together, communicating their results and data, if a full map of the ocean is ever to be achieved.

Seabed 2030 has made impressive progress, mapping almost 19% of the ocean in under 7 years. That said, gaps in the data still remain.

Areas by the coast in West Africa, such as Nigeria and Angola, have active oil industries. It's important to map regions that experience a lot of vessel activity and oil drilling.

Another important area to map is the Mesoamerican Reef in Central America. Currently, the ecosystem is threatened, and many of its species are endangered. Conservation efforts would greatly benefit from having the area mapped in detail.

Lastly, scientists have been studying Antarctic ice to get a better understanding of the climate crisis. Bathymetry data would allow them to measure the changes they're finding in much greater precision.

 Bathymetry and Natural Disasters 

 Marie Tharp's Firsthand Account - Mapping the Mid-Atlantic Ridge 

 AI in the Ocean Sciences 

 Bathymetry, Sea Levels, and Ice-Ocean Interactions  

 Surprising Facts About Marie Tharp 

My name is Elena Shefsky and I am a student at the New York City College of Technology. Growing up in Carroll Gardens, between the Gowanus Canal and Atlantic Basin, made me aware at an early age of the need for ocean and climate conservation.

Through the Girl Talk program, I was able to meet and hear from women in science who are truly making a difference in their fields & the world at large. Lamont and Seabed 2030 are making such great strides in earth and climate research and seeing the dedication of the scientists involved has been an incredibly inspiring experience.