The company provides freight, passenger, and vehicle services between the Isle of Man Sea Terminal, in Douglas, Isle of Man, and four ports in the United Kingdom and Ireland. It is owned by the Isle of Man Government.

There had been various shipping companies serving the Isle of Man before the formation of this company in 1830, but their crossings were irregular, and the vessels used were unreliable. As a result, the island could be cut off for weeks at a time.

The Manx people felt it was essential they should have their own dedicated service. A meeting was held in Douglas in 1829, from which was formed a committee charged with investigating the cost of acquiring a steam packet.

On 30 June 1830, the forerunner of today’s Isle of Man Steam Packet Company was born when the brand new vessel, Mona’s Isle, built at a cost of £7,250, sailed from Douglas to Liverpool on its very first sailing. From the inauguration of the service until January 1832, the company was known as the Mona’s Isle Company. The company then traded as the Isle of Man United Steam Packet, before assuming its present name in July 1832.

The company started with wooden paddle steamers, which soon gave way to the steel “screw” vessels. The “screw” vessels were superseded by turbine steamers, the first being the 1905 SS Viking. The company then replaced the passenger-only steamers with side-loading car ferries, the first diesel car ferry being the 1972 Mona’s Queen (V).

By the turn of the 20th century, the company was serving numerous ports in England, Wales, Scotland, and Ireland. Ports served included Liverpool, Silloth, Whitehaven, Holyhead, Ardrossan, Blackpool, Belfast, and Dublin.

According to Wikipedia