Technology firm Cisco, which is leading the project with the University of Strathclyde, said the trials would also benefit a school and a fish farm.
Orkney, which has among the slowest broadband speeds, is one of six sites for the £4.3 million project, which is funded by the UK government.
The test bed is seen as a crucial way of proving whether 5G can solve the long-standing problems with rural connectivity.
It will include improving mobile connections for the islands’ 175,000 annual tourists, particularly those arriving via cruise liner.
Cisco spokesman Stephen Speirs said: “Tourist density at hot spots such as the Ring of Brodgar and Skara Brae can be a challenge and the source of occasional visitor dissatisfaction.
“Through deploying connectivity to tour buses used on the route from Kirkwall to these sites, we will enable passengers to access dynamic content delivered by Historic Environment Scotland.”
Mr Speirs said that wifi connections would also be improved for ferry crews on the Kirkwall and Shapinsay route because the existing signal is lost as vessels approach Shapinsay.
He said: “This will be a challenging case, as the high-frequency signals will be transmitted over the sea to a slowly moving object - the ferry.
“Delivery of 5G to a moving ferry could be a world first for the project.”
The technology will also be used to remotely-monitor water temperature in a school to detect conditions likely to risk legionella bacteria growth. Conditions in a fish farm will also be monitored.
David Crawford, who runs the 5G research centre at the University of Strathclyde, said: “5G is an opportunity to look at new and innovative ways to improve connectivity in hard-to-reach rural places for a range of users.
“In addition to mobile broadband, we have the chance to address applications in a whole range of sectors including agriculture, aquaculture and utilities.”
He added: “We are delighted to be working with our partners alongside residents and businesses in Orkney, and to show just what 5G may be able to achieve.”