SS Eastfield was a 2,150-ton armed steamship which was torpedoed by the German U-boat SM UB-57 on 27 November 1917. The wreck sits intact at 50°14.255′N 4°42.262′W / 50.237583°N 4.704367°W / 50.237583; -4.704367 at a depth of 50 metres (160 ft) off Mevagissey, Cornwall. The cargo of coal can be found scattered on the sea bed nearby.

The ship was built by Osbourne, Graham & Company of Sunderland in 1901, and owned by The Field Line (Cardiff) Ltd.