Carnival (CCL 0.76%) went from a full stop to full speed ahead, and the result was, as you might expect, a dramatic improvement in its business performance. But what happens now that the cruise line is at the top of its game?Here's what's happened and why 2026 could be a much less impressive year for Carnival.What does Carnival do?Carnival operates nine branded cruise lines, including its namesake brand. It is one of the largest cruise ship owners and operators on the planet. Cruise lines have two main sour ...