Release a decoy, press the Y key. I had Irai mod installed and had 3 destroyers searching me like madmen, sink bombing me like if they were posessed with the thought of killing me. I had absolutely no chance of escaping them while running at 1 knot. The only way I got away was by tricking them with several decoys.
After several hours, I finally escaped the bastards, and when I did, I couldn't believe it myself. I really had it that my fate was to sink right there. I barely had any oxygen, CO2 level skyhigh and battery uncharmingly flat. I think I got up by blowing the main ballast from periscope height.
But I survived the damn thing, and it was good. I always enjoy watching destroyers and escorts close up, but this was one of those times that I found it pleasing to see it fade away on the horizon.