2) There are no lockers on any ferry as far as I know. 3) There are various luggage racks around depending on the particular ferry. On conventional ferries usually near the entrance and also around the various lounges, and decks, which means going up stairs etc. (that is why I use a backpack).

On Greek ferries, there is a specific etiquette for luggage: large, heavy suitcases are typically left in the designated luggage racks on the car deck (the lowest level) immediately after you walk up the boarding ramp. These racks are often organized by your destination island, so it's important to place your bag in the correct section to avoid a scramble when you arrive. You should never leave valuables in these bags, as the area is generally unsupervised once the ship is at sea. Small backpacks, laptops, and "carry-on" sized bags should be taken with you to the upper passenger decks or your cabin. In 2026, while some high-speed "catamaran" style ferries have smaller overhead bins, the traditional large ferries still rely on the "leave it downstairs" system to keep the passenger aisles clear and safe for moving around.