← All notes

Answer: A gyre is a large system of rotating ocean currents. There are five major gyres: the North and South Pacific Subtropical Gyres, the North and South Atlantic Subtropical Gyres, and the Indian Ocean Subtropical Gyre.

What drives the currents

Wind, tides, and differences in temperature and salinity drive ocean currents. The ocean churns up different types of currents, such as eddies, whirlpools, or deep ocean currents. Larger, sustained currents, the Gulf Stream for example, go by proper names. Taken together, these larger and more permanent currents make up the systems of currents known as gyres.

Why they turn: the Coriolis effect

Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. This deflection is called the Coriolis effect. Surface ocean currents on the open ocean are driven by a complex global wind system, and understanding them requires the Coriolis force and the Ekman spiral. Coastal currents are affected by local winds.

"Garbage" gyres

The term "gyre" is sometimes used for collections of plastic waste and other debris found in higher concentrations in certain parts of the ocean. Traditionally, it refers simply to large, rotating ocean currents.

Claims

• id: C1 claim: A gyre is a large system of rotating ocean currents. source: S1 evidence: "A gyre is a large system of rotating ocean currents."
• id: C2 claim: Wind, tides, temperature and salinity differences drive ocean currents. source: S1 evidence: "Wind, tides, and differences in temperature and salinity drive ocean currents."
• id: C3 claim: The deflection of circulating air is called the Coriolis effect. source: S2 evidence: "This deflection is called the Coriolis effect."

Sources

• [S1] What is a gyre?. NOAA. https://oceanservice.noaa.gov/facts/gyre.html . License: US government work, public domain. Accessed 2026-11-04.
• [S2] The Coriolis Effect - Currents: NOAA's National Ocean Service Education. NOAA. https://oceanservice.noaa.gov/education/tutorial_currents/04currents1.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_5gzgfvgd,
  author = {{iinventedlight}},
  title = {{Ocean gyres: the five great rotating current systems}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/ocean-gyres/},
  note = {Permanent ID iil:note:5gzgfvgd. License: CC-BY-4.0.},
}

Markdown

Spotted a mistake? Use the MCP feedback tool or email hello@iinventedlight.com.

For language models and agents: start at /llms.txt. This page in Markdown: /library/notes/ocean-gyres.md.