Alaska Bathymetry
The Alaska Fisheries Science Center provides bathymetry compilations, along with some associated files, for research purposes only. These data may not be used for navigation.
What is bathymetry?
Bathymetry is the measurement of water depth.
Despite centuries of effort, much of the world’s seafloor is unmapped or poorly mapped due to the vast size of the oceans, technical challenges with trying to measure the distance between the sea surface and the seafloor, storms, currents, tides, and sea ice. Alaska is an especially poorly mapped area. As we complete our maps, we are contributing them to GEBCO’s global effort called the Nippon Foundation-GEBCO Seabed 2030 Project, to complete a seafloor map of all ocean areas by the end of this decade.
Why do we study bathymetry?
The Groundfish Assessment Program needs to know the depth of an area because depth is the most important variable for describing the abundance and distribution of bottom-dwelling fish, or groundfish, and invertebrates such as corals and sponges. Derivatives of depth, such as steepness or slope, and roughness or rugosity, are also important for defining species’ habitats. All of our fishery-independent surveys are structured by depth and our population estimates are partially based on depth.
Mapped Alaska Waters?
What is mapped and unmapped in Alaska waters?
That’s a tricky question to answer!
So far, we have published seafloor maps for about half of Alaska waters but that does not mean that we have a depth observation for every location in each of those maps.
To make each map, we gather millions of individual depth observations or soundings, from dozens or hundreds of sources, fix any errors that we can identify, and try to construct a reasonably complete depiction of the area.
Our compilations typically have a resolution, or pixel size, of 100 meters by 100 meters, in order to provide enough detail for our fisheries work. Unfortunately, there are never enough soundings to populate each map pixel, so we make an educated guess on the depth of unsupported pixels based on neighboring pixels with soundings. Thus, while we publish each map as a solid surface, it might only have 30% of its pixels supported by depth soundings.
Alaska Mapping resources
We reviewed our published seafloor maps and determined the amount and type of bathymetric data support within each one. Please let us know about any bathymetry data are available in the gaps we noted!
Downloads
- Eastern Bering Sea TID
- Western Gulf of Alaska TID
- Cook Inlet TID
- Norton Sound TID
- Aleutian Islands TID
- Central Gulf of Alaska TID
- Read me.txt file
Bering Strait Eastern Channel
We created the first detailed and accurate seafloor map of the eastern channel (U.S. side) of the Bering Strait. Then we used the map to define the size and location of the strait’s smallest opening. The tiny size of this minimal opening makes it a bottleneck that restricts the flow of warmer Pacific Ocean water into the colder Arctic Ocean.
Bering Strait Bathymetry Resources
- Strait Science Seminar Recording
- Gateway to the arctic: Defining the eastern channel of the Bering Strait (2023)
Downloads
Beaufort Sea Coast
Erosion rates along Alaska's Beaufort Sea coast, among the highest in the world, exceed 20 meters per year in some areas. We described nearshore seafloor change by comparing older (1945-53) bathymetry data to newer (1985–2018) bathymetry data and related the observed seafloor change to adjacent shoreline change near Utqiagvik, within Stefansson Sound, and immediately west of Barter Island and Kaktovik.
Beaufort Sea Coast Bathymetry Resources
Downloads
Aleutian Islands
We derived the first detailed and accurate estimates of the location, cross‐sectional area, length, and depth of the Aleutian Island passes in 50 years. These passes are important bottlenecks that limit water exchange between the North Pacific Ocean and the Bering Sea. This Aleutians map is an updated version of our 2013 map. We added inshore details to the 2013 version and digitized the shorelines so that we could make a shore-to-shore map.
Aleutian Islands Bathymetry Resources
- Size Of Alaska’s Western Aleutian Island Passes Larger Than Previously Thought
- Passes of the Aleutian Islands: First detailed description (2021)
Downloads
False Pass
Is False Pass a real place?
Yes, it is!
False Pass is the easternmost pass of the Aleutian Islands and one of the smallest, occurring between the tip of the Alaska Peninsula and Unimak Island, but its size and shape were not well described.
Unlike all of the other Aleutian passes, False Pass is configured with both northern and southern inlets. We found that it had two or more inlets to the Bering Sea in the recent past, but that it has only a single northern inlet now (15,822 m2), roughly equivalent in size to the southern inlet, Isanotski Strait (15,969 m2). Navigational charts depict the opposite: two inlets to the Bering Sea now, but just one in older charts (1926–43). This discrepancy inspired a thorough review of the hydrographic history from which we concluded that the second northern inlet did exist and hypothesize that it was a remnant of multiple former openings, or a single large opening, potentially allowing greater northward flow of warmer, fresher Alaska Coastal Current water.
False Pass Bathymetry Resources
Downloads
International Bathymetric Chart of the Arctic Ocean
We contribute our regional Alaska bathymetry compilations to the International Bathymetric Chart of the Arctic Ocean, also known as IBCAO. We also edit the Alaska portion of IBCAO prior to publication. We co-authored IBCAO v. 4 in 2020 and anticipate IBCAO v. 5 to be published in 2024. This Arctic map is a focus area within the global GEBCO organization.
Arctic Ocean Bathymetry Resources
Downloads
Western Gulf of Alaska
We proofed and edited 18 million depth soundings from about 500 different sources to create our Western Gulf of Alaska map. The main findings are abundant features related to glaciation of the shelf of Alaska during the Last Glacial Maximum including abundant end moraines, some medial moraines, glacial lineations, eskers, iceberg ploughmarks, and two types of pockmarks. We developed an integrated onshore–offshore geomorphic map of the region that includes glacial flow directions, moraines, and iceberg ploughmarks to better define the form and flow of former ice masses.
Western Gulf of Alaska Bathymetry Resources
- New Seafloor Maps Reveal Habitat Sculpted by Ancient Glaciers
- Bathymetry and Geomorphology of Shelikof Strait and the Western Gulf of Alaska (2019)
Downloads
Eastern Bering Sea Slope
We created a new, 100 m horizontal resolution bathymetry raster and used it to define 29 canyons of the eastern Bering Sea (EBS) slope area off of Alaska, USA. To create this bathymetry surface we proofed, edited, and digitized 18 million soundings from over 200 individual sources. We also determined that the four pinnacles depicted on National Ocean Service navigational Chart 16006 are fictional, probably just misunderstood observations of dense schools of fish.
Eastern Bering Sea Slope Bathymetry Resources
Downloads
Chignik
We quantified the shallowing of the seafloor in five of six bays examined in the Chignik region of the Alaska Peninsula, confirming National Ocean Service observations that 1990s hydrographic surveys were shallower than previous surveys from the 1920s. Remobilization of land-deposited volcanic ash and redeposition in marine areas - in some locations facilitated by extensive eelgrass (Zostera marina) beds - is the most likely cause of shallowing in the marine environment.
Chignik bathymetry resources
- Volcanoes And Eelgrass Transform Salmon Habitat
- Volcanic ash deposition, eelgrass beds, and inshore habitat loss from the 1920s to the 1990s at Chignik, Alaska (2018)
Downloads
Alaska Bathymetry Archives 2013-2015
Alaska Bathymetry, Sediments, and Smooth Sheets
Norton Sound
Smooth sheet bathymetry of Norton Sound (2015)
Central Gulf of Alaska
Smooth sheet bathymetry of the central Gulf of Alaska (2015)
Cook Inlet
Smooth sheet bathymetry of Cook Inlet, Alaska (2014)