You will love your trip, melsimpress,
Dinners are relaxed most nights, there is a Captain’s welcome and final dinner when you can dress up a bit. But you could always just throw a pretty scarf on over whatever you have on and you will look great. Sorry, that was a bit of a gender specific dress wear comment! Men don’t need a tie or suit, my husband took a dark blazer, but he often took it off cos it was so warm. He has a couple of jazzy shirts that worked well on formal nights. It’s not as fancy as a sea cruise.
Tips in Euro are best.
Enjoy!