Once the ship leaves shore coverage, TravelPass stops working

TravelPass is Verizon's international day pass: $12 a day — $6 in Mexico and Canada, free there on Unlimited plans — and it lets you use your normal talk, text and data in another country by riding that country's networks. It's the thing most people add before a trip and then stop thinking about.

As the ship moves offshore — often beyond roughly twelve miles from land — its own maritime network can take over from shore-based cellular service. Once your phone is on that network rather than a country's, TravelPass no longer applies: a ship in open water isn't a country. Verizon cruise roaming is billed as its own product, Cruise Daily Pass, which you have to add separately.

Cruise Daily Pass: $20 a day, or no data at all

Cruise Daily Pass is $20 per line per day — nearly double the shore rate — charged only on the days you actually use service onboard, in 24-hour sessions. You add it by texting CRUISE to 4004 before or at the start of your cruise, and it's available on select cruise lines only, which is worth checking before you sail rather than after.

Here's the part that catches people, and it's the reason this decision can't be deferred: there is no pay-as-you-go data at sea. Calls without the pass are $1.99 a minute and texts are $0.50 sent and $0.05 received, so voice and messaging do have a metered fallback. Data has none. Verizon doesn't sell it by the megabyte on cruise ships at all. It's the pass or no cellular data — there's no small accidental charge to stumble into, and no way to use a little.

Only 0.5GB is high speed

The pass advertises unlimited data, and that's true in the sense that matters least. Only 0.5GB of it runs at high speed — far less high-speed data than TravelPass gives you on land — and on a phone that syncs photos or backs itself up, that can be gone before you've used it deliberately. After it goes you keep unlimited data at 3G for the rest of the session.

Verizon will then text an offer for another 0.5GB of high speed at $10, and you can accept it more than once inside the same 24-hour session. A heavy day at sea therefore has no ceiling at $20.

Three passes, three different products

A fly-and-cruise trip can involve all three of these on the same calendar day, each charged on its own terms.

Price the ship's Wi-Fi before you sail

Seven days of using your phone daily is $140 per line, which is enough to be worth ten minutes of arithmetic before you leave. Most cruise lines sell their own Wi-Fi package, and for data alone it's frequently the cheaper route.

The two aren't interchangeable, though. Ship Wi-Fi gets your apps working; Cruise Daily Pass is what makes your own number ring. If someone needs to reach you on the number they already have, that's the case for the pass, and it's the only case that the Wi-Fi package can't answer.

What you shouldn't do is leave the decision until you're aboard. Comparing the ship's Wi-Fi tariff against a cellular pass while standing on deck is how people end up buying both.