In "Power at Sea" (International Interactions, 2014) Brian Crisher and I introduce a data set on all of the world's navies from 1865 to 2011 (since updated through 2019).  Our country-year data focuses on warships with ship-based weapons capable of using kinetic force to inflict damage on other structures or peoples. After identifying a country’s active naval forces, we create a measure of naval power based on the aggregate tonnage of the active ships. Additionally, we create count variables for ship types such as aircraft carriers or battleships.