Willem River

The Willem River or Willems River was named during the voyage of the Dutch East India Company (Vereenigde Oostindische Compagnie, or VOC) ship Mauritius in 1618, under the command of Supercargo Willem Janszoon and captained by Lenaert Jacobszoon, and is one of the few features named on a nautical chart made in 1627.

From that information Willems River would almost certainly have been named after Supercargo, Willem Janszoon, the Commander of the ship Mauritius. Janszoon was captain of the Duyfken in 1605-1606, when part of the Gulf of Carpentaria was mapped, during the earliest documented visit to Australia by a vessel from the Netherlands.

Caert van't Landt van d'Eendracht ("Chart of the Land of Eendracht") is a 1627 chart made by Hessel Gerritsz and is one of the earliest charts showing the coastline of Western Australia. The Willems River is located to the extreme left (north) end of the coastline on the chart and a closer view is provided below.

It is believed that the Willems River of 1618 is the Ashburton River (Western Australia).

The chart shows Willems revier, besocht by 't volck van 't Schip Mauritius in Iulius A° 1618 ("Willem's River, visited by the crew of the ship Mauritius in July 1618").

The detail of the rivers position on the chart, backs up the claim that this is the Ashburton River, which, being at 21 degrees 40 minutes south and 114 degrees 56 east, is almost exactly the latitude shown on the chart. The chart is oriented with north to the left, showing lines of latitude from 20th parallel south to the 35th parallel south at the base of the map. The lines of latitude appear to be very accurate, matching closely known features through the length of the chart.

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Wikipedia