巴士海峽
Once in the Philippine Sea the Echo turned southwest heading in the general direction of the Bashi Channel, the strait between Taiwan and the islands north of Luzon, Philippines. The Bashi is the usual northern entrance to the South China Sea and the skipper was sure that it was the Echo's objective, but their track continued well south of the normal course. Then the Echo slowed and came to periscope depth and went active on his fathometer on a short scale which was not suitable for the depth of water. He was lost! While at periscope depth he must have obtained a good fix because the Echo went deep, turned toward the Bashi Channel, and increased speed to 16 knots. After reporting this rapid course correction by slot buoy "Guardfish" rushed after him knowing that the repositioning of US submarines would be nearly impossible on this short notice. As a precaution against collision with a US submarine the skipper changed depth to 100 meters, a depth commonly used by Soviet submarines and one he knew US submarines would avoid. His apprehension was justified when "Guardfish" detected a US submarine clearing to the north at high speed.