[2] U-33 was fitted with two Germania 6-cylinder two-stroke diesel engines with a total of 1,850 metric horsepower (1,361 kW; 1,825 bhp) for use on the surface and two Siemens-Schuckert double-acting electric motors with a total of 1,200 PS (883 kW; 1,184 shp) for underwater use.

[2] On 28 March 1915, U-33 ordered the Great Eastern Railway's SS Brussels to stop.

[3] Instead of doing so, her captain, Charles Fryatt, ordered full steam ahead and attempted to ram U-33, which only just managed to dive in time.

Off Rizeh, on the Turkish coast of the Black Sea she had stopped as one of the small boats was sinking and repairs were being made.

The ship was not carrying wounded at the time, but had a staff of Red Cross workers on board, as well as her usual crew.

The submarine came around again fired a torpedo from a depth of 30 feet, which hit near the engine room, breaking the ship into two pieces.

[7] 24–25 January 1915, it was on patrol in the Bight, an area where enemy battlecruisers were reported.

[7] On 30 January 1915, departed on "Special anti-submarine patrol" but returned owing to engine trouble.

Arrived Cattaro about 15 September and joined the Constantinople Half Flotilla.

Sank 13 S.S. On 5 December was in action with drifter HOLLIBANK in the Straits of Otranto.

Intercepted a neutral Greek ship between Piraeus and Messina and took as prisoner Stanley Wilson, a King's messenger.

U-33 was operating chiefly in the eastern Black Sea and was based on Constantinople or Varna.

U-33 left Cattaro for Kiel en route attacked by a naval trawler on 1 November at about 36°35'E.