On 15 April, engineering casualties and poor weather slowed her progress. The next day, the weather moderated, but intensified again on 18 April. On 20 April, she left the Bering Sea and entered the less violent, but fog shrouded, waters of the Kuril Islands. Two days later, off the entrance to Onekotan Strait she attacked her first enemy target, but failed to score. The next day, S-34 moved into the Sea of Okhotsk to take up her assigned station west of Paramushiro. Ice, two to five feet above the water, still covered the area and the boat retired through the strait to patrol on the Pacific side of the island. 24 April brought another unsuccessful attack on a merchantman and an attempt to close a warship. Two days later, the lookouts observed increased activity by enemy patrol planes. On 27 April, the S-boat again attempted to penetrate the ice, via Mushiru Strait. The same day, she returned to the Pacific; and, on 28 April she headed back to the Aleutians. She encountered mountainous seas in the Bering Sea; but by 1 May, she was at Attu Island. Thence, she continued on to Kiska; remained offshore on 2 May as a storm battered the island; and, on 3 May, she replenished and moved north to intercept any enemy submarines which might be heading for the Gulf of Alaska. On 10 May, she returned to Dutch Harbor. Refit as intelligence estimates predicting a Japanese thrust at Midway Island and the Aleutians were received, S-34 cleared Dutch Harbor on 28 May and stood west to patrol north of Attu. On 29 May, the Japanese Aleutian force sortied from Ominato and headed east, its approach to its target covered by fog and rain. On the morning of 3 June, Japanese planes bombed Dutch Harbor. Second war patrol From the start of her patrol until 11 June, S-34 remained in her assigned area, listening to reports, but sighting no enemy ships. On 11 June, she received news of the Japanese occupation of Kiska and orders to take "maximum offensive action." She headed for Kiska. Diverted back to Dutch Harbor, she replenished on 12 June and got underway again the same day, but returned to Attu instead of going to Kiska. She reconnoitered Sarana Bay, Holtz Bay, and Chichagof Harbor; none showed any activity. On 17 June, she sighted a warship off the Semichi Islands, but