Fact check: How much of the ocean has been mapped by the National Oceanic and Atmospheric Administration (NOAA) as of 2025?

1. What advocates and reports actually claim — the specific, extractable assertions that matter

The supplied materials make several clear, narrow claims that can be extracted: NOAA-led expeditions mapped over 250,000 km² of deep seafloor in Hawai‘i and Johnston Atoll in 2024, and this activity was credited with increasing modern mapping coverage of U.S. Pacific Islands and territories by roughly 5% ^[1]. Other documents emphasize NOAA’s role in prioritizing areas for future seafloor mapping off the U.S. West Coast and improving data access through geospatial products and ship-track services, but they do not offer a single percent figure for total ocean mapping by NOAA ^{[2] [3]}.

2. Why none of these sources answers the “what percent mapped” question directly

All provided analyses show NOAA materials concentrating on regional accomplishments, campaign outputs, and planning rather than an aggregated coverage metric. The Pacific Islands mapping piece and EXPRESS campaign summaries are operational and project-focused, reporting square-kilometer gains and mission outputs without translating those into a global or national percentage of seafloor mapped ^{[1] [4]}. The NCCOS assessment cited is purpose-built to identify priority areas for future work, not to report cumulative mapping totals, reflecting an organizational emphasis on strategy rather than aggregate accounting ^[2].

3. The most concrete achievement reported: 250,000 km² and a 5% regional boost

Both independent summaries describe the same operational result: six Okeanos Explorer expeditions produced more than 250,000 km² of new deep-water bathymetry, which NOAA framed as increasing modern mapping coverage of the U.S. Pacific Islands and territories by about 5% ^[1]. That is a verifiable, bounded accomplishment: it documents a specific area mapped during a defined campaign and quantifies a regional percentage change, not a percentage of the total global or national ocean area mapped by NOAA.

4. How NOAA frames progress: tools, campaigns, and public access, not a single metric

The documentation underscores data integration and accessibility — NOAA’s Ocean Exploration Data work with ArcGIS Online and EXPRESS campaign contributions emphasize operational layers, ship tracks, and public products rather than consolidated coverage statistics ^{[3] [4]}. This pattern indicates NOAA prioritizes producing actionable datasets and improving the usability of expedition outputs for science and management, while leaving broader synthesis—like a single “percent mapped” figure—to future cross-agency or national mapping plans ^{[3] [4]}.

5. Planning documents show where gaps remain and how NOAA intends to proceed

NOAA’s NCCOS assessment focused on prioritizing seafloor mapping Offshore California, Oregon, and Washington signals ongoing recognition of gaps and the need for strategic allocation of mapping resources ^[2]. The emphasis on prioritization and “filling U.S. gaps by 2030” in planning texts implies that current mapping coverage is incomplete and that NOAA and partners are organizing multi-year efforts to address uneven regional coverage rather than claiming near-complete mapping of U.S. waters ^{[2] [5]}.

6. Reconciling different viewpoints and what's omitted from these sources

The supplied materials present a consistent operational narrative: NOAA advances mapping through targeted expeditions and improves data dissemination, yet they omit any agency-wide percentage of ocean mapped. What’s absent is a consolidated, up-to-date accounting that aggregates project-level gains into a single metric for either U.S. waters or the global ocean. The documents prioritize campaign outcomes, regional percent changes, and tools—all useful—while leaving policymakers and the public without a simple headline figure to describe total NOAA mapping coverage ^{[1] [3]}.

7. Bottom line: what can be stated with confidence and the practical next steps

Based on the provided analyses, the only firm, attributable claim is that NOAA expeditions added >250,000 km² of deep seafloor mapping for the U.S. Pacific Islands and territories in 2024, yielding a regional coverage increase of about 5%; no source among the supplied materials reports a comprehensive percentage of the ocean mapped by NOAA as of 2025 ^[1]. To obtain an authoritative overall percentage, a reader should seek a NOAA or interagency synthesis report that aggregates project outputs into national or global coverage figures, or a formal statement from NOAA explicitly providing that metric, neither of which appears in the provided documents ^{[2] [3]}.