Where to find naval-history photographs

What are good free or paid sources for naval photography?

Useful collections include Drachinifel, MaritimeQuest, the UK National Archives, the National Maritime Museum, and the U.S. Naval Institute; Imperial War Museums can be expensive.

Drachinifel and MaritimeQuest provide specialist collections, while the UK National Archives, National Maritime Museum, and U.S. Naval Institute offer major institutional sources. Imperial War Museums is identified as a notably costly source for licensed material.