Oho, a question I can answer (more or less)! I just got finished rereading a favorite of mine, "A War Like No Other," by Victor Davis Hanson, which details the Peloponnesian War between Athens and Sparta just a few decades after the Persian Wars. It's less a when and what happened about the war, but a how the war was fought, with each chapter detailing the various methods used to fight this previously unknown type of war in the Western world. And, due to the nature of the conflict, one chapter is devoted entirely to ships and sea battles. Greeks at the time used a ship called a trireme, which during the start of the war was manned by various poor unlanded urbanites, but would eventually be manned by anyone who could be paid or forced to row due to the horrific fatalities of the war. Wasn't a pretty job, as Hanson describes:

The most cramped and unpleasant positions in the 120-foot-long ship probably belonged to the 54 thalamites. These poor crewmen rowed from deep in the hold (thalamos), crammed in a scant eighteen inches above the water. Leather pads in their oar holes in theory kept the waves out. But seawater always splashed in anyway - the ship was honeycombed with over one hundred such holes - and bilge water also seeped through the planking near their feet. Sailors were probably soaked on and off throughout the entire voyage. As a rower pulled and leaned back and then pushed forward, his rear scooted to and fro along the bench, explaining why seamen considered seat cushions as important as good oars - and why rump blisters were a common complaint.

Because of the crossbeams and the other seamen rowing directly above their heads, the thalamites could see almost nothing. The sweat from the two superior banks of rowers - the posteriors of the seamen above were more or less in the thalamites' faces - drenched them as well. The comic poet Aristophanes joked that the thalamites were often farted upon and even showered with excrement from the straining oarsmen above, a scatological reference that he may have derived from the common and collective real-life miseries of the veterans of the theater audience. Sweat, thirst, blisters, exhaustion, urine, and feces - all this was in addition to the billows of the sea and the iron of the enemy.

...

Right above the lowly thalamites sat the middle bank of 54 zygiante oarsmen, who were perched on the ship's main crossbeams (zyga). They, too, could not see the water and rowed through portholes. But at least these "crossbeamers" in the middle bank had more room and did not have to contend with the legs and rumps of the oarsmen above.

The top row of two banks, the most prestigious slots and so often the best paid, was occupied by 62 thranites in total, port and starboard. These elite rowers were above the splashing of the seas and enjoyed constant breezes. They sate on an outrigger, and besides fresh air, sunlight, and greater room could alone of the crew see their oars hit the sea and communicate with the rowers below. If they were the most vulnerable to enemy missiles, thranites were also the most likely to get out of the ship alive if it was rammed and sank.

Hanson, pp. 237-238

Further on, he details actual battle amongst these vessels, which were pretty terrifying and horrific even before the old Greek "rules of war" were thrown out the window as the first ever civil war in Western culture consumed them:

The blind world of a Greek warship suddenly ended when the trireme either hit the enemy or was rammed itself. "Quite simply, over the entire harbor arose the crash of the colliding ships and the cry of desperate struggling men, killing and in turn dying," Diodorus wrote of the Athenian fleet as it smashed into its Syracusan counterpart in the Great Harbor. "No one could hear any of the commands once the boats hit each other and their oars smashed together, and at the same time was added the racket of the men fighting on the ships and their supporters on shore." Diodorus reminds us, "When a ship was caught by several triremes, and struck in every direction by their massive rams, once the water poured in, the ship and its entire crew were swallowed by the sea."

When triremes collided, men were immediately jarred from their seats, and bedlam followed. If they were on the attack, the orders - how the boatswain's commands could be heard in the midst of battle is unknown - went out to back to immediately to disengage the ram from the struck ship, lest the doomed enemy seamen and marines swarm onto their own decks.

In turn, if struck broadside at ten knots with a wooden ram weighing four to five hundred pounds and sheathed and tipped with bronze, seamen either jumped into the water or boarded the attacker in the few seconds before their own trireme, penetrated at the waterline, was partially submerged. When the Athenian assembly voted to put down the rebellion at Mytilene or to launch an armada against Sicily, most of the 6,000 to 7,000 voters crammed onto the rocky Pynx - the meeting place below the Acropolis - were themselves veterans of this macabre warfare at sea: rowers and rammers first, participants in democracy second.

At top speed a trireme could power into a targeted hull with fifty tons' worth of destructive force and send in thousands of gallons of seawater in seconds. Indeed, sometimes the first hit put such an enormous hole in the enemy hull that the ship was immediately swamped. But a Greek warship could attack only in one direction. Even its own missile troops offered little offense amid-ships. In some cases skilled crewmen could orchestrate ramming attacks against a number of ships that found themselves unable to turn about, knocking apart targeted triremes even as they sought to flee past, to shore.

Hanson, pp. 241-242

Frequent drowning was relatively common inasmuch as few Greeks swam on a regular basis to guarantee their survival in rough seas. When a ship was hit, it was not easy to get out from the cramped rowing bench, climb through dozens of panicky seamen, avoid jagged wooden debris, missiles, and boarders, and then swim the thousands of yards to shore. On a crippled ship, the key to survival was to manage to disengage, row away, and allow the crew to jump overboard well distant from the enemy - such as the Athenians who escaped after their defeat at Notium in 408, losing 22 ships but saving most of the sailors.

What percentage of a ship's crew was lost when a trireme was submerged is not recorded. Yet there are plenty of descriptions in Greek literature to suggest that on occasion a ship's entire complement of seamen could be killed, lost, or taken prisoner. Inclement weather - as, for example, off Cape Athos in 411 (12 of 10,000 saved) or at the battle of Arginusae in 406 - seemed to ensure that sinking warships would doom their entire crews.

Hanson, pp. 246-247

I'd highly recommend the book to read through, as it's fascinating even for someone with no real interest in the history of Antiquity. But, needless to say that without extremely thorough training, discipline, and courage, rowing into battle in a Greek trireme was not exactly a surefire way to survive to retirement.

Normally you didn't have slaves rowing a warship. For Athens at least it was supposed to be comprised of free citizens. In theory, rowing a trireme required close cooperation between the rowers, one off stroke could cause a tangle of oars and leave the ship sitting in the water as an easy target.

At least one scholar (van Wees) makes a case for there being slaves who served regularly and that the Athenian anger over losses at Arginusae was that it was a wholly citizen crewed.

Also, triremes didn't really sink as they're all wood and not that heavy. Instead they'd just settle into the water. The crew was at risk of drowning or being killed by the enemy if they came to recover the wrecked ship (which could be repaired and put in service).