Both sides used oared galleys (known as quinquiremes) with as many as 300 rowers inside and space for 120 marines. Each ship had a ram (known as a rostrum), which aimed to smash a hole into the enemy ship to disable or even sink it. Sometimes they were used to shear off the enemy oars on one side, leaving the enemy unable to manoeuvre. Skillful crews, such as the Carthaginians, were faster and could manoeuvre better, giving them and advantage in ramming tactics.
The Romans preferred boarding tactics where their marines had the advantage in hand to hand fighting on the ships. They developed a corvus (a drawbridge with a spike at the end that could be dropped into the enemy deck, preventing its escape). This gave them an advantage at the battles of Mylae and Ecnomus.
Because these ships were almost like human propelled torpedoes, they were not very comfortable, had little space for food, and usually the crews had to sleep on the shore every evening. Nor were they very seaworthy and the Romans suffered catastrophic losses in several storms at sea during the First Punic War.
By the end of the First Punic War, it was said that the Romans had lost 700 ships and the Carthagians 500.