You may not have considered a cruise vacation because you're worried you'll get seasick and be miserable all the time.
As someone who is prone to getting carsick, I completely understand. While it is possible you might get queasy on board a cruise ship, most people report that they have few problems.
Today's ships, especially the large mainstream ships, have stabilizers that keep the rocking of the sea to a minimum. After all, they wouldn't want you sitting down to a fine meal in the dining room only to have your plates skidding off the table!
Most of the time, you'll barely be aware you're in the water.
Also, a lot of cruise itineraries stay in relatively calm waters such as protected seas and inside passages. If you think seasickness might be a problem for you, consider a trip that hugs the coast or skirts through something like Alaska's inside passage for your first cruise.
But chances are seasickness will be the last thing on your mind, and you'll have a wonderful time on board.
Hey, you can always take some Dramamine along for emergencies.