At least 36 enemy submarines active according to the U.S. Joint Intelligence Committee. Daily summary dated 13 March 1942

An item reported that the enemy divided her submarine over the next probably positions: 11 at varying distances off the North American Coast between Cape Hatteras and 100 miles east of Newfoundland (which one near Hatteras, two or three are close to the coast between Cape Henry and Nantucket and three to the southward of Cape Race), 3 submarines in the area just covered and the longitude of the Azores, 1 north of the Azores, four are between the longitude of the Azores and the Bay of Biscay, two southeast of Bermuda, seven in the West Indies-Caribbean area (1 north of eastern Cuba, three south of Cuba, 1 near St. Lucia), 1 off British Guiana, around 4 between Iceland and Ireland and 3 off Liberia, totally around 36 submarines.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 93 dated 13 March 1942.