When it launched in 2000, Royal Caribbean International’s 3,114-passenger Explorer of the Seas was the largest passenger ship in the world. Despite refurbishments that increased tonnage, Explorer of the Seas is now far from the largest at sea. The refits have added the exhilarating activities Royal Caribbean has been introducing on its ships (ice-skating rink, surfing simulator), though, so it feels more modern than you would expect. After 14 years in the Caribbean, Explorer of the Seas relocated to the other side of the globe to sail in Australia, the South Pacific, and Alaska starting in 2015.