Arguably one of the biggest mistakes first-time cruisers make is thinking you won't spend any money once you've booked the trip. That's because in theory, when you board the ship, your lodging, food, and gratuities are already paid for.
But Finkelstein said you'll likely come across a few instances where you'll need cash. First, it's common courtesy to tip for room service, and if your stateroom steward does a great job, it can be nice to give them an additional tip beyond the prepaid gratuities.
Plus, if you go on excursions, you should have cash ready to tip the tour operator, driver, and any other guide you encounter during your vacation.
While most cruise ships have ATMs, they typically come with a hefty charge. Finkelstein suggests saving a few dollars by taking out cash ahead of time.