Quick summary: the Greek and Ottoman Turk navies fought two inconclusive battles during the wars, and a Turkish light cruiser acted as a raider. The Greeks had one modern heavy ship, the Italian-built armored cruiser Averoff (purchased with some privately-donated funds) and three older, small, oddly-designed battleships. The Turks had purchased two German battleships with three twin turrets (a "too early" attempt at a all-big gun layout) and had two modern light cruisers. The Turks had also rebuilt several of their old, decaying ironclads into modern-looking warships, but only one of these could have been an effective battleship and this one (the Messudieh) had wooden dummy guns substituted for its main weapons (which were available but never added). Both sides had destroyers and torpedo boats as well. The fleets seemed evenly-balanced enough in this little arms race to prevent either side from a decisive victory at sea (the story was different on land however, where Greece, Serbia and Bulgaria tore apart Turkey's European domains and then attacked each other, only a couple years before the far greater bloodbath of WWI).
For learning about the Turkish fleet consult an obscure but well-illustrated book called "the Ottoman Steam Navy".
