Numbers are fine but sometimes the best way to communicate scale is visually.  The image above is what it would have looked like if the largest passenger liner of roughly 100 years ago, RMS Titanic, was followed closely by the largest cruise ship of today, MS Allure of the Seas. Judged by gross tonnage, which is a measure of the volume of the ship rather than the weight, the MS Allure of the Seas at 225,282 GT is almost five times larger than the Titanic, at 46,328 GRT.  This comparison is an approximation as the tonnage rules have changed over time. Nevertheless, the image tells the story. Thanks to Dr. Alan Rice for passing the image along.