Like all post-E8 British E-class submarines, E30 had a displacement of at the surface and while submerged. She had a total length of and a beam length of. She was powered by two Vickers eight-cylinder two-stroke diesel engines and two electric motors. The submarine had a maximum surface speed of and a submerged speed of. British E-class submarines had fuel capacities of of diesel and ranges of when travelling at. E30 was capable of operating submerged for five hours when travelling at. E30 was armed with a 12-pounder QF gun mounted forward of the conning tower. She had five 18 inch torpedo tubes, two in the bow, one either side amidships, and one in the stern; a total of 10 torpedoes were carried. E-Class submarines had wireless systems with power ratings; in some submarines, these were later upgraded to systems by removing a midship torpedo tube. Their maximum design depth was although in service some reached depths of below. Some submarines contained Fessenden oscillator systems.
E30 joined the 11th Submarine Flotilla, based at Blyth, Northumberland on commissioning. From 23 to 28 February 1916 E30 patrolled off Denmark and Norway with the intention of capturing ships carrying Iron ore from Norway to Germany, and to attack any German submarines that were escorting the Iron ore ships. No ships at all were seen during the patrol. E30 patrolled in the Kattegat in March 1915, and was damaged by heavy seas on 16 March, while on 18 March she stopped the Norwegian steamer Kong Inge, carrying a mixed cargo to Germany, off Anholt. She put a prize crew aboard Kong Inge and ordered the merchant ship to Leith for examination. On 5 AprilE30, together with the newly commissioned submarines and set out from Blyth with orders to patrol between Denmark and the Orkneys in the hope of intercepted German submarines. E30s patrol was cut short when she suffered a battery explosion on the morning of7 April, killing four men and forcing her return to base. On 15 May 1916, E30 set out for a patrol in the Kattegat, and on 18 June she encountered the German steamer, whose crew abandoned ship after E30 fired a warning shot. E30 fired two torpedoes, which missed, and then sank the steamer with gunfire. On 2 June E30 was returning from a patrol off the coast of Norway when she spotted two British cruisers returning from the Battle of Jutland, which she signalled, but one of them,, opened fire on E30 in response. Minotaur claimed to have sunk a submarine, but E30 returned home safely. On 3 July she encountered the Norwegian steamer Prunelle off Lindesnes in southern Norway. E30 fired two warning shots, but was driven away by the Norwegian torpedo boat. Norway raised a protest about the attempt to stop Prunelle, claiming it took place in territorial waters.
