I always seem to run out of time on sea days on Seabourn. It is not that the days are jam packed with things to do, it is that you are put into a sort of "kick back and Seabourn takes care of me" mode.
There are some differences between the smaller and larger ships, but for the most part a sea day on either can consist of a leisurely breakfast al fresco or, more formally, in The Restaurant followed by a morning lecture or soak in a whirlpool with a Bloody Mary or champagne and then, fully relaxed, a trip to the spa...or even a complimentary 10 minute Massage Moment on deck.
After a late morning siesta, book or chat, a nice lunch is served followed by a cooking demonstration and the blood sport of Trivia.
There is a conflict later in the afternoon between High Tea (awesome scones and wonderful loose tea varieties...as well as finger sandwiches, etc.) and that second soak in the whirlpool with champagne. A later afternoon lecture is usually available. Bridge is usually also organized. Speaking of bridge, bridge tours are offered.
On most cruises there is a Galley Market Lunch which is an incredible feast which on the smaller ships is set up in the Galley. On the larger ships that isn't really practical, but it is still quite an event in the Restaurant.
All of this is followed by cocktails and a chat at the Sky Bar, then after getting ready for dinner, drinks in The Club followed by dinner and then an evening show and/or dancing, casino, etc.
See, it is a very busy day...and you get to do it more than once!