---
source: https://iinventedlight.com/library/notes/ocean-gyres.md
title: "Ocean gyres: the five great rotating current systems"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA, What is a gyre?, US government work, public domain; NOAA, The Coriolis Effect - Currents: NOAA's National Ocean Service Education, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "ocean science: marine life and currents"
tags: ['noaa', 'currents', 'gyres', 'ocean']
sources:
  - id: S1
    title: "What is a gyre?"
    publisher: NOAA
    url: https://oceanservice.noaa.gov/facts/gyre.html
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "The Coriolis Effect - Currents: NOAA's National Ocean Service Education"
    publisher: NOAA
    url: https://oceanservice.noaa.gov/education/tutorial_currents/04currents1.html
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# Ocean gyres: the five great rotating current systems

**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).