The company is based in Penzance, and also owns Isles of Scilly Skybus Ltd, an operator of fixed-wing aircraft services to the Isles of Scilly, and Westward Airways, an operator of sight seeing flights.
The original Scillonian was built for the Isles of Scilly Steamship Company in 1925 by Ailsa Shipbuilding Co Ltd of Troon, Scotland to carry 400 passengers and cargo. The first regular trip of this vessel took place on Thursday 2nd February 1926 from St. Mary's to Penzance. Following this ship Scillonian II entered into service in 1956, built by Thornicroft of Southampton, she was later sold and ran a service between the mainland and Lundy. A second ship operated for a while named Queen of the Isles. At approx 500 tons she was smaller than Scillonian II and was used to augment the larger ship at busy times. She was also used to run charter services to the Islands from other ports. On her sale she went to operate an inter-island service in the Pacific.
The present Scillonian III was purpose built for the Steamship Company in May 1977. Scillonian III is the third passenger ship of this name and currently in service for passengers and cargo 8 months of the year. Due to the number of tidal currents which meet off Lands End, and the need for a shallow draught to allow access to the Islands, the sea journey to Scilly can be rough. For this reason Scillonian III was fitted with a "Flume" stabilizer system.
During the winter, when Scillonian III is out of service, a cargo only service is provided by Gry Maritha.