Jacob Jansz. Quaeckernaeck (or Quackernaeck or Kwakernaak) was a Dutch seaman and Captain of the Liefde, the ship which transported William Adams to Japan in 1600.
Quaeckernaeck was allowed to leave Japan on 1604 on a Red Seal Ship provided by the daimyo of Hirado, together with another former crew of the Liefde, Melchior van Santvoort, with the destination of Patani in the Malay Peninsula.
From Patani, Quaeckernaeck joined the fleet of Cornelis Matelief de Jonge, a compatriot and his nephew, on August 19, 1606. He died however in a naval engagement where Matelief destroyed half of the Portuguese armada near Malacca, on September 21, 1606.
Melchior van Santvoort returned directly to Japan from Patani, and continued being active in trade between Japan and Southeast Asia.