The opportunity to see characters on the ship is endless. Our first encounter was with Minnie, who we took a picture with right in the terminal before boarding.
You are bound to see the characters while walking around the ship as there is always someone wandering the halls. They also have set times that the characters are available for autographs and pictures. Be prepared to stand in line, especially the first few days. There are also many character sightings on Castaway Cay, with the adorable creatures in their beach gear. The princesses are also around and there are a couple of princess gatherings. One line (likely a long one) but you get to meet each princess in one shot.
Don’t feel like standing in line? Don’t fret! There is a character breakfast where four characters come and take pictures with each person present. The breakfast is assigned and definitely one to attend. We took pictures with the ever popular mice and chipmunks. There is also a goodbye event the last night on the ship giving you one last opportunity to see the characters and princesses. The lines this last day only took a few minutes.