HMS Rainbow was a Rainbow-class submarine built for the Royal Navy during the 1930s.

The Rainbow-class submarines were designed as improved versions of the Parthian class and were intended for long-range operations in the Far East.

[1] For surface running, the boats were powered by two 2,200-brake-horsepower (1,641 kW) diesel engines, each driving one propeller shaft.

[2] Rainbow ran aground in the English Channel off Ventnor, Isle of Wight, on 22 January 1932.

She is believed to have been sunk on 4 October in a collision with the Italian merchant ship Antonietta Costa, which reported striking a submerged object at 03:30, followed by a huge underwater explosion while sailing in convoy from Albania on that date.