Jan Carstensz was a Dutch explorer, of whose life little is known.

In 1623, with two ships, the Pera and Arnhem, Carstensz navigated the Gulf of Carpentaria. Landing in search of fresh water for his stores, he met a group of Aborigines. Carstensz described them as "poor and miserable looking people" who had "no knowledge of precious metals or spices".

On May 8, 1623, Carstensz and his crew fought a skirmish with 200 Aborigines at the Carpentier River . Cartensz had named the small river near Cape Duyfhen (along with the cape itself) in honor of Pieter Carpentier , at that time Governor-General of the Dutch East Indies.

Carstensz Pyramid, Irian Jaya, Indonesia was named by him. He sighted the glaciers on the peak of the mountain in 1623. Carstensz was ridiculed in Europe when he said he had seen snow near the equator.

He also named several other features along Australia's north coast.