On evenings proposed as 'informal', a suit or smart jacket and trousers, with or without a tie, for the men is suggested and the ladies have further opportunities to look elegant in cocktail dresses or trouser suits.

A 'casual' recommendation often covers evenings spent in port or when a special event such as a deck party is scheduled. 

During the day, attitudes are very relaxed and informality is key. Casual clothing is quite sufficient  during the days at sea and for time spent ashore.