Princess Irene was built by William Denny and Brothers Ltd, Dumbarton for British Columbia Coastal Steamships. She was launched on 20 October 1914. With her sister ship Princess Margaret, she was built to serve on the Vancouver – Victoria – Seattle route. Her port of registry was Victoria. Princess Irene was requisitioned by the Royal Navy on her completion and converted to an auxiliary minelayer. She had a complement of 225 officers and men. She was 395 feet (120 m) long with a beam of 54 feet (16 m) and a draught of 17 feet (5.2 m). She was propelled by four steam turbines which could propel the ship at 22.5 knots (41.7 km/h).
In May 1915, Princess Irene was moored in Saltpan Reach, on the Medway Estuary in Kent between Port Victoria and Sheerness, being loaded with mines in preparation for deployment on a mine laying mission. At 11:14 GMT on 27 May, Princess Irene exploded and disintegrated. A column of flame 300 feet (100 m) high was followed a few seconds later by another of similar height and a pall of smoke hung over the spot where Princess Irene had been, reaching to 1,200 feet (400 m). Two barges lying alongside were also destroyed. A total of 352 people were killed, including 273 officers and men, and 76 dockyard workers who were on board. On the Isle of Grain a girl of nine was killed by flying debris, and a farmhand died of shock. A collier half a mile (800 m) away had its crane blown off its mountings.
The victims, whose bodies were recovered, were buried at Woodlands Road Cemetery, Gillingham. A memorial service led by Randall Davidson, the Archbishop of Canterbury for the victims was held at the Dockyard Church, Sheerness on 1 June 1915.
A Court of Inquiry was held into the loss of Princess Irene. Evidence was given that priming of the mines was being carried out hurriedly by untrained personnel. A faulty primer was blamed for the explosion. A worker at Chatham Dockyard was named as a suspect, but a thorough investigation by Special Branch cleared him of any blame.