Easbound Pacific passages generally require travel along very high latitudes (50-60 deg), because the major mid-latitude winds and currents are westerly.
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The major surface currents are
wind generated (as most other oceanic currents are), creating a large clockwise gyre (circular feature) in the
north Pacific and a counterclockwise gyre in the
south Pacific. An equatorial countercurrent flows in the opposite direction of the adjacent currents of the major gyres north and south of the equator.
In the north, the Kuroshio
current flows eastwards across the Pacific from
Japan to the coast of North America, where it turns south as the
California current, then flows west again as the north equatorial current. Small counterclockwise gyres exist in the Gulf of
Alaska (Alaska current), and in the northwestern Pacific basin , where the flow near the Asian coast is known as the Oyashio current.
The Southern
Pacific Ocean has a counterclockwise subtropical gyre , consisting of the westward flowing South equatorial current in the north, the southwards flowing
Australia current, the Antarctic circumpolar current that flows east (at 50 - 60 Deg. S.), and the
Peru (Humboldt) Current that flows northwards near
South America.
There are numerous other small current systems are found throughout the
Pacific Ocean basin and its marginal seas.