Join the Wolf Pack. On April - May 1943 ranged against them were 58 U-boats in 3 patrol lines; Specht (Woodpecker) with 17 boats south of Greenland on the western side of the Air Gap; Meise (Bluetit) with 30 boats east of Greenland covering the northern route, and Amsel (Blackbird) with 11 boats, south of Meise covering the southern route.
https://en.wikipedia.org/wiki/Convoy_ONS_5