United States
Dictionary of American Naval Fighting Ships Online
US-Naval Vessel Register — temporarily off-line
Bluejacket
Haze Gray & Underway Naval History Center
The US Navy in the Pacific 1941 – 1945
United States Navy Patrol Squadrons
The National Association of Destroyer Veterans
PT Boats, Inc. (PT Boats – Bases – Tenders)
American Merchant Marine at War
Japanese
Nihon Kaigun — Imperial Japanese Navy Page
Organizations of Imperial Japanese Army & Navy
The Transpacific Voyage of the I-400
Imperial Japanese Navy
Imperial Japanese Navy Signals and Instructions
Steve Eckardt's Imperial Japanese Navy Submarine Page
Netherlands
Royal Netherlands Navy Warships of World War II
Shiplovers Homepage Dutch merchant ships from 1870 till present
Britain, Commonwealth, and Dominion
Royal Navy
The Red Duster (British Merchant Navy)
Germany
German Kriegsmarine
Chronik des Seekrieges 1939 – 1945 (German)
U-Boot.net
Misc. and General
Finnish Navy in World War II
World War 2 Cruiser Operations
International Journal of Naval History
Regia Marina Italiana (English and Italian)
British and other Navies in World War 2 Day-by-Day
Danish Naval History (English, Danish)
Naval Weapons, Naval Technology and Naval Reunions