At 21.42 hours on 20 Jun, 1940, the Otterpool (Master Thomas Prince) in convoy HGF-34 was hit by one stern torpedo from U-30 and sank about 130 miles west of Ushant. The master, 21 crew members and one gunner were lost. 16 crew members were picked up by HMS Scarborough (L 25) (Cdr N.V. Dickinson) and landed at Liverpool.

The Otterpool and another vessel of the same convoy had been missed during an attack by the same U-boat earlier that day. She was also missed by an attack from U-51 (Knorr) at 15.33 hours on 20 June in grid BF 1983. The U-boat had reported two explosions, but saw no other effects on two ships due to bad visibility. In fact, the Andalusian and the Otterpool were missed. According to the xB-Dienst reports, the BdU assumed that there had been hits on the Fellside (misidentification of the Andalusian) and the Otterpool.