HMS K1 was a First World War steam turbine-propelled K-class submarine of the Royal Navy.

She had been patrolling on the surface as part of a flotilla of submarines operating in line ahead.

The collision occurred at approx 17:35 and after consultation with the rescued submariner officers and concluding that the K1 could not be saved, Blonde opened fire with one of her 4 inch guns and sank the submarine with a few shells at 19:10 hours.

[2] The submarine was powered by two oil-fired Yarrow Shipbuilders boilers each supplying one geared Brown-Curtis or Parsons steam turbine; this developed 10,500 ship horsepower (7,800 kW) to drive two 7 ft 6 in (2.29 m) screws.

Submerged power came from four electric motors each producing 350 to 360 horsepower (260 to 270 kW).