It varied over time as more and more banks of oars were added - the figure of 300 is an average for the quinquireme (five banks).
One of the largest naval battles was the battle of Leyte Gulf. It was a battle that included a large fleet of naval vessels and also a large number of personnel were involved.
By the 480 BCE treaty with Carthage, Xerxes sought to have the strong Carthaginian navy tie up any augmentation of the easter Greek fleets from Sicily during his invasion of mainland Greece in that year. Carthage sought to extend its control over the Greeks in Sicily at the same time, but lost much of its fleet in a storm.
Spain.
hotwell
An outer commercial harbour and an inner protected naval harbour.
The minimum allowable flash point for all fuels on US naval vessels is 140oF (60oC)
These vessels carry SLBMs.
Some vessels carry boats so there is no lower limit.
The punic Wars were a contest between Rome and Carthage for control of the Western Mediterranean. When Rome destroyed Carthage it achieved that goal, and in then taking retribution against Macedonia for supporting Carthage, launched itself into the Eastern Mediterranean.
Naval (please note spelling) vessels are usually taken to be the military vessels of a nation. Navel = belly button.
Just that-- a fleet. To be more specific, a naval fleet. Oftentimes, terms used to describe aerial vessels are also used to describe naval vessels.
The answer depends greatly on definitions. By many accounts the Allied invasion fleet assembled for D-Day was history's largest, including roughly 5,000 vessels, and more than 100,000 people. If we define "largest" to mean greatest firepower, then the largest fleet might be that assembled for the attack on Iraq in 1990, which involved many nuclear aircraft carriers and a variety of heavy and light surface vessels.