[Jimbuna]

Otto Kretschmer was a great believer in evading ones pursuer on the surface using the dark, fog, rain etc. to your advantage rather than diving below the surface where he believed the Kaleun was more restricted in his options.

U-99 passed Lousy Bank late, running ahead, surging forward, sliding through the satiny waves, leaving the miles behind. Kretschmer went below to talk, to count tonnage, to debrief. A watch officer and two lookouts remained on the bridge. Then it was night, and the enormous frame of the surrounding darkness, and the sub sliding through the sea with nothing else around her. She was clipping through the waves and had much to report back to BdU in Lorient when she arrived. Then later, the watch officer spotted a destroyer, suddenly, unexpectedly; and here, at this sighting, the watch officer made a mistake. Ignoring Kretschmer's standing orders to remain surfaced in the event of a possible attack, he dove. Half a minute, and U-99 was gone from the surface. She reached a comfortable depth, and then she evened up, crawling through the dark fathoms of the sea, invisible, deadly, creeping through the gloom below the surface.

The rest is history, shortly afterwards U-99 was forced to the surface and Kretschmer was a POW:

http://davidfairbankwhite.com/excerpt_bitter.html