Equatorial Undercurrent

oceanography

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 26, 2026

Quick Summary

The Equatorial Undercurrent is an eastward-flowing ocean current located near the equator, typically between 160 and 500 feet (49 to 152 meters) below the surface. This undercurrent flows at speeds up to 5 feet per second (1.5 m/s) and is approximately 1,000 feet (305 meters) deep and 640 miles (1,030 km) wide.1

It is driven by a pressure gradient created by higher sea levels on the western margins of tropical oceans. In the absence of a strong Coriolis force at the equator, this pressure gradient drives the westward-to-eastward flow of the undercurrent, counteracting the surface currents which are typically westward. The Equatorial Undercurrent is part of the broader wind-driven circulation system of the oceans.2

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

ocean current
Equatorial currents
This is called the Equatorial Undercurrent. It attains speeds of more than 1 metre per second at a depth of nearly 100 metres. It is driven by higher sea level in the western margins of the tropical ocean, producing a pressure gradient, which in the absence of a horizontal…
Read More
This is called the Equatorial Undercurrent. It attains speeds of more than 1 metre per second at a depth of nearly 100 metres. It is driven by higher sea level in the western margins of the tropical ocean, producing a pressure gradient, which in the absence of a horizontal…
Read More