Thrill Engineer and University Professor Brendan Walker Concludes Royal Caribbean International Will Astound Adrenaline Junkies MIAMI, May 23, 2016 – Royal Caribbean International’s Harmony of the Seas, the world’s largest cruise ship, claims another record as home to the tallest slide and most exhilarating adventure at sea: Ultimate Abyss. The hair-raising, 10-story slide is …