re: Missing Submarine

Me neither. In oceanography they're called near-inertial waves with the main velocity occurring in the horizontal plane. Google says the Java Sea can have them up to 2 meters a second or nearly 4 knots. The highest near-inertial wave vertical velocity I could find, assuming one could force a sub deeper, was 0.6 meters per second about 1 knot. Not near enough force to drive a controlled sub deeper. Near-inertial waves also decay with depth.

The statement about under water waves being a suspected cause was likely a face saving measure. Otherwise, in naval history I'd expect more occurrences, catastrophic or not, would have been reported by different navies world wide.