The primary emphasis of the Arethusa-class cruisers was a design speed of 30 knots (56 km/h; 35 mph), to allow them to lead destroyers in combat.

In support of this goal, they were the first cruisers to use destroyer-type high-speed steam turbines and oil-fired boilers were chosen to save weight and increase their power to meet the specification.

The Arethusa class were powered by four direct-drive steam turbines, each driving one propeller shaft, which produced a total of 40,000 indicated horsepower (30,000 kW) and gave a speed of about 28.5 knots (52.8 km/h; 32.8 mph).

The turbines used steam generated by eight Yarrow boilers at a working pressure of 235 psi (1,620 kPa; 17 kgf/cm2).

[4] They carried 840 long tons (853 t) tons of fuel oil[2] that gave the ships with cruising turbines a range of 5,000 nautical miles (9,300 km; 5,800 mi) and 3,200 nmi (5,900 km; 3,700 mi) for those without, both at 16 knots (30 km/h; 18 mph).