Returned to full commission on 14 February 1922, she was ordered to New London, Connecticut, where she was placed in ordinary again on 21 June 1922 for engine alterations by the prime contractor for her construction, the Electric Boat Company.

In January 1923, she moved south to the Caribbean Sea to participate in winter maneuvers and Fleet Problem I, conducted to test the defenses of the Panama Canal Zone.

In the years that followed, her division rotated between exercises and patrols in the Philippines during the winter and operations off the China coast during the summer.

In 1932, S-30′s division was ordered back to the eastern Pacific Ocean, and, on 2 May 1932, she departed Manila bound for Pearl Harbor, Hawaii, which became her new home port.

Transferred back to the United States East Coast, S-30 departed Pearl Harbor on 19 May 1937 and arrived at New London on 8 August 1937.

With World War II raging in Europe and German U-boats raiding shipping in the western Atlantic Ocean and the Caribbean, S-boats like S-30 were assigned to Submarines, Patrol Force (known as Submarines, Atlantic Fleet after February 1941) and conducted training and the development of tactical skills.

Departing New London on 31 January 1942, she hunted for enemy submarines along her route which took her via Bermuda and Mona Passage into the Caribbean Sea.

While en route, engine trouble forced her into Mare Island for repairs, but on 1 August 1942 she resumed her northward voyage.

On 12 August 1942, S-30 departed the submarine base at Dutch Harbor on Amaknak Island off Unalaska in the Aleutians to begin her fourth — and first offensive — war patrol.

After the completion of her overhaul, she provided training services to the West Coast Sound School from mid-February 1943 into March 1943.

On the afternoon of 27 April 1943, she returned the waters off Attu but was unable to determine the extent of damage the strike inflicted on Japanese forces and facilities.

On 24 May 1943, S-30 departed Dutch Harbor to begin her seventh war patrol and headed west again, this time bound for the northern Kuril Islands.

Her guns set the vessel on fire, but as it burned, a Japanese destroyer appeared on the horizon and began closing the surfaced submarine at high speed.

She patrolled on both sides of the Kuril Island chain and across the shippung lanes leading to Soya Strait and to Yokosuka, Japan.

She took periscope photographs of Japanese facilities on various islands and sighted several targets, but was unable to close on most of them and was unsuccessful against those she attacked.

On 20 July 1943, she attacked what appeared to be an inter-island steamer but which turned out to be a Japanese warship that steamed straight down the torpedo track and dropped six depth charges in quick succession.

Her sound operator reported two hits, breaking-up noises, and distant depth charging, but the damage went unverified by postwar examination of Japanese records.

Fog interfered with her first attempt to shell Matsuwa, but it cleared off early on the morning of 15 September 1943 (local date) as she neared the firing point with her crew at battle stations.

Her crew attempted to install a new firing pin, but it was a fraction of an inch too short, and she had to abandon her bombardment effort.

Within a week of arriving at Dutch Harbor, S-30 headed south to San Diego, where, with others of her class, she provided training services for the West Coast Sound School for the remainder of World War II.