The MS Nindawayma was a passenger and automobile ferry, whose last active service was on Lake Huron, operated by the Owen Sound Transportation Company Limited; under contract to the Ontario Ministry of Transportation. In Canadian service she served the Highway 6 route between Tobermory and South Baymouth, Manitoulin Island from 1989 to 1992 alongside the MS Chi-Cheemaun.
By 1977, the UK/Spain-Balearic Islands services for which they were built had ceased, the ships were sold, the Monte Castillo to Manx Line (later Sealink-Manx Line) and renamed as the Manx Viking for service between Heysham, England and Douglas, Isle of Man. Following a controversial reverse takeover in 1986 by the Isle of Man Steam Packet company, she worked a season painted in Steam Packet livery, initially alongside the Mona's Isle (ex- Free Enterprise III) followed by Antrim Princess (subsequently renamed Tynwald) before Manx Vikings lease was terminated and she was returned to her owners (the parent Sealink company, by now part of Sea Containers Ltd, who had actually funded the takeover). In 1987 she was briefly renamed Viking for the delivery voyage to new Norwegian owners Det Stavangerske Dampskibsselskap, for whom she sailed in service under the name Skudenes. Then followed in 1989 another sale into service with the Government of Ontario, crossing the Atlantic as Ontario No.1 before final renaming as MS Nindawayma.
During Manx service she enjoyed an unrivalled reputation for reliability with passengers and was able to put to sea in weather conditions which forced her competitors to remain in port. Her arrival created a marked change in Manx traffic flows eventually resulting in the financial collapse of the rival Isle of Man Steam Packet Co, its and subsequent amalgamation with Sealink-Manx Line.
She initially carried the white and blue livery of Manx Line, but after this company ran into financial difficulties and was taken over by British Rail-Sealink, she received the BR corporate monastral blue hull, white upperworks and red funnel. She differed from other Sealink ships in carrying a gold-coloured scuplted "three legs of man" on her funnels rather than the standard BR double chevron. Publicity images were released of her painted in the Sea Containers era Sealink livery of white hull with blue trim, but these were mockups and the colours never applied. Instead, after the Steam Packet takeover her blue hull was hurredly given an overpaint of black, retaining the BR red funnels (rather than the differently-hued Steam Packet red). Following the takeover, the crew persisted in flying the Manx Line house flag, rather than the management-mandated Steam Packet one
It was initially intended that she would be retired from Manx service following the amalgamation of Sealink-Manx Line and The Steam Packet. Services would be concentrated on the Heysham-Douglas route with a strengthened two-ship service using the larger Monas Isle and Antrim Princess. The Steam Packet's year-round Liverpool-Douglas services were to be abandoned. In the event, trade union problems delayed the transfer of Antrim Princess from Stranraer, while Mona's Isle proved unserviceable. Instead Monas Isle was withdrawn after six months and Manx Viking remained for another season. Manx Viking was eventually replaced by the cargo-only RORO vessel Peveril leaving Antrim Princess / Tynwald as the only passenger vessel on the route. In so doing the combined company avoided an expensive charter as the otherwise surplusPeveril was owned by the Steam Packet, not leased and had just been released from charter on the Heysham-Belfast route. The changes in manning brought about by the Manx Viking withdrawal, and Pevereril's route transfer were some of the centres of dispute of the 1980s British national seamen's strikes.
If Manx Viking had been withdrawn as originally intended, she would have been transferred to Weymouth and renamed Earl Henry for service on the route to Cherbourg. This never took place due to the delayed availability of the Antrim Princess.