Carnival's megaship Jubilee has a star on board, and it's not the captain. The Wall Street Journal profiles Kyndall "Fire" Magyar, a 31-year-old cruise director whose fans book entire vacations just to sail with her. As the on-board emcee, hype woman, and de facto cruise mascot, she's on from dawn past midnight, running game shows, hosting deck parties, delivering announcements, and posing for 70 to 100 selfies a day. Magyar, who grew up cruising Carnival and now commands a 13-person "Fun Squad," plus almost 300,000 social-media followers, sums up the job this way: "Make sure you like people and don't like sleep." "She had the boat rocking," one recent cruisegoer said of Magyar, noting she flew her family in from Florida to Texas just so they could sail with her.

The piece follows Magyar through bad-weather scrambles, football-season schedule tweaks (Cowboys and Texans games can trump a sail-away party), rapid-fire costume changes between activities, and the trade-off of months at sea away from her husband,…