Fleet Week is a United States Navy, United States Marine Corps and United States Coast Guard tradition in which active military ships recently deployed in overseas operations dock in a variety of major cities for one week. Once the ships dock, the crews can enter the city and visit its tourist attractions. At certain hours, the public can take a guided tour of the ships. Often, Fleet Week is accompanied by military demonstrations and air shows such as provided by the Blue Angels.
source: wikipedia – Fleet Week New York