View of Cape Maria van Diemen from Cape Reinga few kilometers away.

The following information is from the Wikipedia article:
Cape Maria van Diemen is the westernmost point of the North Island of New Zealand. Being close to the northern tip of the Aupouri Peninsula, many people in New Zealand also incorrectly believe it to be the northernmost point (that title goes to the Surville Cliffs, 30 kilometres to the east and slightly further north).
The cape was named by Abel Tasman after the wife of his patron, Anthony van Diemen, Governor General of Batavia (now Jakarta) in January 1643. It is - along with the Three Kings Islands - one of only two geographic features in New Zealand to retain the names given to them by Abel Tasman.