HMS E25 was a British E-class submarine built by William Beardmore and Company, Dalmuir.

British E-class submarines had fuel capacities of 50 long tons (51 t) of diesel and ranges of 3,255 miles (5,238 km; 2,829 nmi) when travelling at 10 knots (19 km/h; 12 mph).

[1] E20 was capable of operating submerged for five hours when travelling at 5 knots (9.3 km/h; 5.8 mph).

E25 was armed with a 12-pounder QF gun, mounted forward of the conning tower.

[2] E-Class submarines had wireless systems with 1 kilowatt (1.3 hp) power ratings; in some submarines, these were later upgraded to 3 kilowatts (4.0 hp) systems by removing a midship torpedo tube.