You will not see Whales
You may see porpoise and turtles,
You are in the Med, Agean and Caspian so land is not far away. To pick up on Poobear's point. If you are lucky enough to see Stromboli during the day, fantastic what a sight.
Actually, when you are at sea on a Euro cruise, then that is the time too chill out and get ready for the next port. You will have so seen much on shore, at sea is the chill, sleep and drink time.
Also hops are short in the med so you will come back from one port and then eat, drink and sleep, ready to start again the next day.
Dont worry about what to see at sea, you will be on overdose I promise from the land. Posted as someone who has done these ports on at least 6 diferent occasions and never gets tired of them