In Kauai, we did Koloa Zip Line, bur we were there for a land based vacation, not a cruise. We picked that one because it had a tandem option where my 7 year old could essentially be my backpack, but she also had her own pulley to hang onto as well. Tons of lines, maybe 8 if I recall correctly, with the last one being 1/2 mile long. They also allow for nontraditional zipping, such as Superman style or even upside down (which my older daughter and husband dared to do). This was my first zip line experience and it was awesome. I felt safe the entire time, but believe me, it was heart-pounding...and my 7 year old still talks about how awesome it was.