RMS Arundel Castle was a British ocean liner and Royal Mail Ship which entered service in 1921 for the Union-Castle Line.

She should have been completed in 1916, under the name Amroth Castle,[1] but with the advent of World War 1, construction on the ship was put on hold until November 1918.

[1] She received a refit in 1937, with her four funnels being reconfigured into two, with new Babcock-Johnson boilers,[4] her hull lengthened, and her bow remodelled from a straight stem to a more modern, angular design.

After being released by the Admiralty, she was converted back to a passenger liner to provide a service for emigrants traveling to South Africa.

The ship's furnishings and accessories—including the chronometers, captain's armchair, steering wheel, crockery and sterling silver cutlery—were offered as gifts.