Carnival Cruise Line is widely known for having one of the most relaxed dress codes in the industry, but they do enforce certain boundaries, particularly in the Main Dining Room (MDR). During the day, attire is extremely casual, focusing on swimwear, shorts, and t-shirts. However, "Cruise Casual" evenings in the MDR prohibit beach flip-flops, swimwear, sleeveless shirts for men, and baseball caps. On "Cruise Elegant" nights, the rules step up; while you'll see everything from suits to nice jeans with a blazer, items like gym shorts and t-shirts are strictly forbidden. Enforcement can vary by ship and staff; while some guests report being turned away for wearing cargo shorts at dinner, others find the staff quite lenient. In 2026, the general consensus is that as long as you look "neat and intentional" and avoid beachwear or pajamas at dinner, you will have no issues.