They take the iron at security.

The fire-risk category catches most people: irons, travel steamers, kettles, candles and anything with a heating element are banned on most ships, because a fire at sea is a different category of emergency. Extension leads with surge protection go too, for electrical reasons on a ship's supply — and people pack them precisely because cabins have very few sockets. Alcohol above the line's allowance is taken at security. All of it is held until the end of the cruise.

Because cases are handed over at the terminal and delivered to cabins over several hours, with early evening arrival being common — so the first afternoon is spent unable to reach anything you packed. It's the most reliably reported surprise of a first cruise. Swimwear is the item people most regret leaving in the case, since the pools are open and the ship is at its emptiest that afternoon. Medication, documents and a change of clothes go with you too.

Less than folklore suggests, and it varies enormously. Dress codes have relaxed considerably across the industry, from black tie on some lines to a jacket and no tie on others, and the number depends on the sailing length rather than being fixed — check your line's own description, since this is the area where old information circulates most. One outfit worn twice is entirely normal. And formal night is optional on most lines, with the buffet and casual venues unaffected.

Roughly half what most people bring. Daywear can be worn more than once and evening items reused — on a typical seven-night sailing that's around ten clothing items rather than eighteen. Cabins have almost no floor space and the case has to fit under the bed, so an oversized hard case is a genuine problem. And the ship sells anything you turn out to need, at a markup that's still cheaper than dragging it there.

A document problem, and it's generally non-refundable. Multi-country itineraries can have requirements that differ from ordinary travel, and some need documentation even for ports where nobody disembarks — check with the cruise line and the official government source for every nationality on the booking. Separately, check your insurance covers cruising specifically: medical care on board is charged privately, domestic health arrangements generally don't apply at sea, and evacuation from a vessel is in a different cost category entirely.