Orkney ferries operate an inter-island ferry service. All of them are available to foot passengers, and many allow cars. There is also an inter-island flight service.
A regular bus service operates around Orkney, and there are taxi companies. You can also hire bikes in Stromness (Mainland) and in Kirkwall (Mainland), and on some of the islands, including North Ronaldsay and Stronsay.
Please be aware that the majority of the watch sites are remote and not well-served by public transport.
Visit https://www.orkney.com/plan/getting-around to find out more.