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Answer: The ocean averages about 3,682 meters (12,080 feet) deep. The deepest point, Challenger Deep in the Mariana Trench in the western Pacific, is about 10,935 meters (35,876 feet).

Average depth

The latest average was calculated in 2010 by NOAA and Woods Hole scientists from satellite measurements. They found the seafloor bumpier and more mountainous than expected, so the average came out less than earlier estimates. That is why online sources give a range of numbers.

Deepest point

Challenger Deep lies at the southern end of the Mariana Trench, southwest of Guam. It is named for HMS Challenger, whose crew first sounded those depths.

An uneven bottom

Because the seafloor is so uneven, depth varies widely from place to place.

Claims

• id: C1 claim: The average depth of the ocean is about 3,682 meters. source: S1 evidence: "The average depth of the ocean is about 3,682 meters (12,080 feet)."
• id: C2 claim: Challenger Deep is approximately 10,935 meters deep. source: S1 evidence: "Challenger Deep is approximately 10,935 meters (35,876 feet) deep."
• id: C3 claim: The ocean bottom is not flat or uniform. source: S2 evidence: "its bottom is not flat or uniform"
• id: C4 claim: The average was calculated in 2010 using satellite measurements. source: S2 evidence: "was calculated in 2010 by scientists from NOAA and Woods Hole Oceanographic Institution"

Sources

• [S1] How deep is the ocean?. NOAA. https://oceanservice.noaa.gov/facts/oceandepth.html . License: US government work, public domain. Accessed 2026-11-04.
• [S2] How deep is the ocean? - NOAA Ocean Exploration. NOAA. https://oceanexplorer.noaa.gov/facts/ocean-depth.html . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_qkw84fpd,
  author = {{iinventedlight}},
  title = {{How deep is the ocean?}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/ocean-depth/},
  note = {Permanent ID iil:note:qkw84fpd. License: CC-BY-4.0.},
}

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