Cruise line Carnival has launched a wearable gadget that allows services on board its ships to be personalised for guests.
The Ocean Medallion can be worn as a necklace, clip or keychain - or carried in a passenger's pocket.
It will connect to onboard facilities, tracking meal orders or automatically unlocking guests' cabins as they approach the door, for example.
One analyst said it would have to be easy to use to entice holidaymakers.
Details of the project are being outlined at two events at the CES tech show in Las Vegas.
'Needs to be flawless'
The Ocean Medallion will connect with onboard systems on the first specially modified cruise ship later this year via internet of things technology.
Other ships in the Princess Cruises fleet will then adopt the system.
It was a "great example of novel uses for smart devices", said Martin Garner, a tech analyst at CCS Insight.
"But, because people go on cruises as a relaxing holiday, the system will have to work flawlessly and be super-easy to use," he told the BBC.
He also noted that, just like upgrading a big hotel, the venture would likely be a costly one - which adds "a degree of risk" for Carnival.
Miles of cable
The first ship to feature the system is the Regal Princess. 75 miles (121km) of cables, more than 7,000 sensors and 4,000 digital screens were installed in 10 days in Italy.
"It's going to almost be invisible to guests," the company said.
"They're not going to realise how much [technology] is in here."
Holiday resorts and cruise ship brands, including Carnival's rival Royal Caribbean Cruises, increasingly offer visitors access to various services via smart bands or wearable gadgets.
The undertaking could perhaps foreshadow what life in a future smart city or internet of things-powered shopping complex might be like.
But Mr Garner noted not everyone had the capabilities of a cruise line.
"City officials don't typically have the budget to do grand-vision schemes like the Carnival re-fit," he said.
"In fact, most cities are chronically short of budget."
Connection technologies built in to the Ocean Medallion include Bluetooth and near field communications (NFC), according to the travel firm.
This will allow passengers to:
- unlock their cabin doors automatically as they approach
- find the location of friends and family onboard the ship
- pay for merchandise without using cash or a credit card
- navigate from one place to another on the vessel
- connect guests to a gambling platform accessible around the ship
The service will be offered first to passengers on the Regal Princess ship from November. It will then be expanded to the Royal Princess and Caribbean Princess ships in 2018.
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