 He received his training at the Royal Netherlands Naval College and the frigates HNLMS "Tromp" and HNLMS "Abraham Crijnssen", where he was an ensign.In 1988 he received additional training at the ship HNLMS "Van Kinsbergen" and became a lieutenant (junior grade) ("wachtofficier").As a reservist for the Royal Netherlands Navy, Willem-Alexander was promoted to Lieutenant Commander in 1995, Commander in 1997, Captain at Sea in 2001, and Commodore in 2005.