RMS Empress of Ireland was a British-built ocean liner that sank near the mouth of the Saint Lawrence River in Canada following a collision in thick fog with the Norwegian collier Storstad in the early hours of 29 May 1914, en route to Liverpool. Although the ship was equipped with watertight compartments and, in the aftermath of the Titanic disaster two years earlier, carried more than enough lifeboats for all aboard, she foundered in only 14 minutes. Of the 1,477 people on board, 1,012 died, making it the worst peacetime maritime disaster in Canadian history.

Fairfield Shipbuilding and Engineering built Empress of Ireland and her sister ship, Empress of Britain, at Govan on the Clyde in Scotland. The liners were commissioned by Canadian Pacific Steamships or CPR for the North Atlantic route between Liverpool and Quebec City. The transcontinental CPR and its fleet of ocean liners constituted the company's self-proclaimed "World's Greatest Transportation System". Empress of Ireland had just begun her 96th voyage when she was lost.

The wreck of Empress of Ireland lies in 40 m (130 ft) of water, making it accessible to advanced divers. Many artifacts from the wreckage have been retrieved, some of which are on display in the Empress of Ireland Pavilion at the Site historique maritime de la Pointe-au-Père in Rimouski, Quebec, and at the Canadian Museum of Immigration at Pier 21 in Halifax, Nova Scotia. The Canadian government has passed legislation to protect the site.

Empress of Ireland was the second of a pair of ocean liners ordered by Canadian Pacific Steamships during their early years in operation on the North Atlantic. In 1903, Canadian Pacific officially entered the market for trans-Atlantic passenger travel between the United Kingdom and Canada. In February of that year, they had purchased Elder Dempster & Co, through which they obtained three ships from Elder's subsidiary, the Beaver Line. These ships were Lake Champlain, Lake Erie and Lake Manitoba, with Lake Champlain being the first to sail on the company's established route between Liverpool, England and Montreal, Quebec, the following April. The line proved to be successful on the North Atlantic trade, as in that first year, thirty-three westbound crossings were completed by those three ships, on which a combined total of 23,400 passengers travelled in third class, most of them emigrants bound for Canada.

In early 1904 work commenced at Fairfield Shipbuilding and Engineering in Glasgow, Scotland. The liners were designed by Francis Elgar and were specified to be twin screw liners with service speeds of 18 knots (33 km/h; 21 mph). Both were of identical appearance, with two funnels and two masts, with equal passenger capacity of just over 1,500. In the early planning stages, their intended names were to have been Empress of Germany and Empress of Austria, but were later changed respectively to Empress of Britain and Empress of Ireland, following the implementation of a policy that any future Canadian Pacific ship named in the Empress format would be respectively named after a dependency or colony of the British Empire.

The ship's keel was laid down on 10 April 1905 for hull number 443 at Fairfield's berth number 4 next to her sister ship, Empress of Britain, which was being built. Empress of Ireland's length was 570 ft (170 m) overall and 548.9 ft (167.3 m) between perpendiculars. The beam was 65.7 ft (20.0 m) and her depth was 36.7 ft (11.2 m). Empress of Ireland had twin four-bladed propellers, each driven by a quadruple-expansion steam engine. Between them the two engines were rated at 3,168 NHP and gave her a service speed of 18 knots (33 km/h; 21 mph). She had twin funnels and two masts.

Empress of Ireland's safety features included ten watertight bulkheads which divided the hull into eleven compartments which could be sealed off through the means of closing twenty-four watertight doors. All eleven bulkheads extended from the double bottom up to directly beneath the Shelter Deck, equivalent to three decks above the waterline. By design theory, the vessels could remain afloat with up to two adjacent compartments open to the sea. However, what would prove to be the fatal flaw in her design in 1914 was that, unlike aboard Titanic where the watertight doors could be closed by the means of a switch on the ship's bridge, the watertight doors aboard Empress of Ireland were required to be closed manually. Also, in the wake of the Titanic disaster, Empress of Ireland, like many other liners, had her lifesaving equipment updated. When she first entered service in 1906, she had been equipped with standard wooden lifeboats, which in 1912 were replaced with sixteen steel lifeboats mounted in conventional radial davits, under which were stored another twenty-six wooden collapsible lifeboats, all of which combined had a capacity of 1,686 people, 280 more than the ship was licensed to carry.

Empress of Ireland was launched on 27 January 1906. With her original configuration she required a crew of 373, and had berths for 1,542 passengers in four classes on seven decks.