Carnival shares have advanced about 29% so far this year.After the tumultuous seas of early pandemic days, Carnival (CCL 3.92%) (CUK 4.47%) has sailed into calm waters. The world's biggest cruise operator recently reported a quarter filled with records, beat analysts' earnings estimates, and raised full-year guidance for a third time.The recipe for such success? Carnival has put the focus on controlled spending, cost savings in key areas such fuel, and has made efforts to increase guests' onboard spending.A ...