Top 10 navy facts

Bolivia. Although Bolivia has been landlocked since the War of the Pacific in 1879, it still maintains its navy, which patrols Lake Titicaca and Bolivia's larger rivers. The Navy serves as a symbol that the country has not given up on regaining its lost access to the sea. As of 2008, the Bolivian Naval Force had approximately 5,000 personnel.

8. Most American aircraft carriers are powered by two reactors. The only exception was the early-constructed USS Enterprise, having an eight-reactor propulsion design, with each A2W reactor taking the place of one of the conventional boilers in earlier constructions. Enterprise was meant to be the first of a class of six, but construction costs ballooned and the remaining vessels were never laid down. The design was replaced by two-reactor Nimitz class.

Boarding. Since the Romans were primarily a land-based army, they lost several sea battles due to lack of naval skills. The corvus, a boarding ramp with two steel spikes, was the Roman answer to this problem. It secured Roman naval dominance in the Mediterranean Sea for several centuries.

It burns slower. The introduction of brown powder, which burned less rapidly than black powder, allowed to use longer barrels, which resulted in greater accuracy. Slower-burning powder decreases firing stresses, allowing guns to last longer and to be manufactured to tighter tolerances.

It was a disappointment. Kaitens had a very limited diving depth, which in turn limited the diving depth of the host submarine. This is one of several factors blamed for the very poor survival rate of submarines armed with kaitens: eight submarines being lost for the sinking of only two enemy ships and damaging several others.

Great Lakes freighters. Since the freshwater lakes are less corrosive to ship than the salt water of the oceans, many of the Lakers remain in service for long periods and the fleet has a much higher average age than the ocean-going fleet. The St. Mary's Challenger, built in 1906, is currently the oldest boat on active duty on the Lakes.

Radars. USS San Antonio, the lead ship of her class of amphibious transport dock, is designed to deliver up to 800 Marines ashore. As the vessel incorporates stealth features, its major antennas are mounted on platforms inside two Advanced Enclosed Mast/Sensor systems rather than on traditional mast yardarms.

French submarine cruiser "Surcouf". Surcouf was the largest French submarine cruiser having served during the Second World War. The boat was lost during the night of 19 February 1942, in the Caribbean Sea, possibly after colliding with an American freighter. Surcouf was named after the French privateer Robert Surcouf. It was the largest submarine built until surpassed by the first Japanese

Sends acoustic waves. The Long Range Acoustic Device (LRAD) is an acoustic hailing device developed by LRAD Corporation to send messages and warning tones over longer distances or at higher volume than normal loudspeakers. LRAD systems are used by law enforcement, government and defense agencies, as well as maritime and commercial security companies to broadcast audible notifications and warnings over distance.

Japan. On the night of 31 May – 1 June, three Japanese Ko-hyoteki-class midget submarines, each with a two-member crew, entered Sydney Harbour, and attempted to sink Allied warships, ultimately killing 21 sailors.