For thousands of years, strength at sea has been one of the defining military factors of any world power. Naval strength is used to respond to territorial disputes as well as enforce maritime borders and protect national interests. Today's navies are often required to operate thousands of miles away from homeports with combat not necessarily requiring line-of-sight. Couple these qualities with the expansive reach of carrier aircrafts, naval helicopters and UAVs and the oceans become a lethal battlefield all their own.
The listing below includes battleforce ships made up of aircraft carriers, frigates, destroyers, corvettes, torpedo boats, patrol boats, amphibious support craft and landing craft (regardless of onboard technology employed, crew training, fleet quality, etc...). Auxiliary vessels are also included. Landlocked nations are NOT penalized for the lack of a standing naval force and are, thus, excluded from this particular list.
Sources: CIA.gov, CIA World Factbook, wikipedia.com, public domain print and media sources and user contributions. Some values may be estimated when official sources are lacking.