Princess May was a steamship built in 1888 which was operated under a number of different names and owners. The ship is best known for having been involved in a grounding in 1910 which left the ship jutting completely out of the water, which became the subject of a famous shipwreck photograph.

This ship, although it served under other names, is best known as the Princess May. The Canadian Pacific had a fleet of ocean-going ships with names beginning with “Empress". It was decided that the planned fleet of coastal liners (which in 1901 did not yet exist) would have names beginning with “Princess.” Princess May was named after Mary of Teck, who was known as “May”. Later Princess ships were not named after actual princesses, however.

Princess May was built and launched under the name Cass in Hebburn, on the south bank of the River Tyne in North East England, in 1888 by Hawthorn, Leslie & Co., Ltd. for the Formosa Trading Company. Hawthorn Leslie built another ship, the Smith, at the same time for the Formosa Trading Company.

Cass was 249 feet (76 m) long, 33-foot (10 m) beam, 18-foot (5.5 m) depth of hold, 1717 gross and 1394 registered tons. Power was supplied by two triple-expansion engines, each one driving a separate propeller. Each engine had three cylinders, which, ranging from high pressure to low pressure, were 19, 30, and 50 inches (1,300 mm) in diameter. The stroke on all cylinders was 33 inches (840 mm). Steam was generated by three coal-fired boilers. The ship was built with electric lighting installed by Rankin Kennedy of the Woodside Electrical Works, a Glasgow firm.

Cass served in the China coast trade from 1888 to 1901 under a number of different owners and names, including Arthur, Cass (again), Ningchow, and Hating, the ship's name in 1901. During the ship's service on the China coast there was a mutiny on board and the ship was attacked by pirates.

The arrival of Cass and Smith at Taiwan was called the “shipping event of the year” for the China coast. The Formosa Trading Company had been organized by the modernizing governor of Taiwan, Liu Mingchuan, based on the advice of a former manager of the China Merchant Steam Navigation Company. A contemporary source states that the ostensible purpose of ordering the two steamers was modernization of Taiwan, but the actual goal was to compete with the China Merchant Steam Navigation Company and its two allied English companies for the passenger traffic on the Yangtze River and between Shanghai and Tientsin.

The China Merchant Steam Navigation Company was able to defeat this challenge, and the Formosa Trading Company became defunct. Cass and Smith were then run by Taiwan's governor, Liu Mingchuan but in an unprofitable manner. Cass and Smith were said to have cost £59,000 and were not expected to be profitable in service.

In 1901, the newly formed Canadian Pacific Railway Coast Service, operating in British Columbia under superintendent James W. Troup, wanted a steamship to meet the high demand for traffic on the route to southeastern Alaska, but did not want to wait for a year or more to build a new ship. Cass, by then operating under the name Hating (or Ha-Ting), was available. The Coast Service purchased Hating, and in May, 1901, under the command of Capt. A.O. Cooper, brought it across the Pacific to the west coast of Canada. Princess May was the first ship acquired by then-newly formed Canadian Pacific Railway Coast Service.