Navy Day takes place on October 27, 2018. In the United States, the Navy League of the United States organized the first Navy Day in 1922, holding it on October 27 because it was the birthday of President Theodore Roosevelt, who was a naval enthusiast.
Although meeting with mixed reviews the first year, in 1923 over 50 major cities participated, and the United States Navy sent a number of its ships to various port cities for the occasion. The 1945 Navy Day was an especially large celebration, with President Harry S. Truman reviewing the fleet in New York Harbor.
In the 1970s, the "birthday" of the Continental Navy was found to be October 13, 1775, and so CNO Admiral Elmo R. Zumwalt worked with the Navy League to define October 13 as the new date of Navy Day. However, Navy Day in the United States is still largely recognized as October 27. (With material from: Wikipedia)