Cruise policies can look similar until one small detail catches you out. A rule that is fine on one line may cost you money or get an item confiscated on another. These 11 examples show why checking your own cruise line before you pack can save you trouble at the terminal or onboard.

The Muster Drill
The safety briefing is not optional. International SOLAS rules require newly embarked passengers to undergo safety drills, including mustering, before the ship departs or immediately on departure. Even if you have cruised before, you still have to complete the required safety process for your sailing.
Outside Alcohol
Carnival lets guests 21 and older carry on one sealed 750-milliliter bottle of wine or champagne on embarkation day. Hard liquor and beer are prohibited, and excess or prohibited beverages can be confiscated and discarded without compensation. Check your own line before packing because alcohol limits differ.
The Drinking Age
The drinking age can change with the itinerary. Royal Caribbean sets the minimum at 21 on cruises originating in North America or the Caribbean. Many sailings originating in South America, Europe, Asia, Australia and New Zealand use 18 instead.
Door Decorations
Carnival allows stateroom-door decorations only if they are fire-retardant. Magnets and Command Strips are allowed, but tape and glue are not. Decorations cannot go on balconies, and flammable items can be removed without compensation.

Smoking and Vaping
Carnival bans smoking and vaping in staterooms and on balconies. A violation can bring a $500 charge, and Carnival says guests may also be disembarked. Smoking is limited to designated areas, so do not assume your balcony is fair game.
Cruise Elegant Dress
Carnival uses a Cruise Elegant dress code on certain evenings. Select cruises of five days or less have one such night, while cruises of six days or more have two. Swimwear, athletic clothing, sheer clothing and ripped or cut-off T-shirts are not permitted in the main dining room on those evenings.
Automatic Gratuities
On Carnival, cruise service gratuities are charged to your Sail & Sign account unless you prepaid them. The amount can be adjusted onboard after it has been posted. Checking your account during the cruise can help you avoid a surprise at the end.
Specialty Dining Cancellations
Royal Caribbean requires specialty-dining cancellations at least 24 hours before the reservation time. Cancellations inside that window generally carry a $25-per-person fee, and no-shows are charged too. Some venues have higher fees, so check the policy when you book.

All-Aboard Time
If you explore a port on your own, watch the ship’s all-aboard time. Royal Caribbean says it is generally about 30 minutes before departure and should be verified onboard and near the gangway. The line also says the ship will not wait for guests touring independently.
Pool Chair Saving
Royal Caribbean says pool chairs are first come, first served. If a chair is unattended for more than 30 minutes with no sign of the guest returning, crew can remove the belongings and place them in lost and found. A towel alone does not hold the chair all day.
Power Strips and Extension Cords
Extra outlets can cause trouble at security. Royal Caribbean prohibits extension cords, power strips and multi-plug outlets unless an item falls under a stated exception or special review. Check your line’s prohibited-items list before tossing one into your suitcase.
The Bottom Line
Cruise lines often handle the same issue differently. A few minutes with your own line’s current rules before you pack can prevent a confiscated item, an unexpected fee or a missed reservation.