Many ancient shipwrecks have been found, but only of commercial boats, never of armorclads. The ruins were preserved only partly. Given that we haven't found any ruin of the ancient warships, we have been based in some innuations in the anctient texts. These innuations are rare and difficult to interpret.
Anyway, taking into account the findings and the relevant studies that have been done, it is certain that the ancient Greek people had an important naval knowledge and have probably been the most powerful naval power of the ancient times.