The Navy still doesn't know what their submarine hit Friday. "Probably not another sub," they say.

"We have no data to suggest that there were any other vessels of any kind, submarine or otherwise, operating in the area at that time," Pacific Fleet spokesman Lt. David Benham says. "Every indication is that it struck a geological feature."

Trouble is, there are not supposed to be any "geological features" there. Not to mention that Los Angeles-class attack subs are equipped with a vast array of sensors that should have picked up any undersea mountains with ease.

One esoteric theory being kicked around is that this was a new underwater topological feature thrown up somehow by the same Sumatran quake that created that killer-tsunami. Experts say that's not too likely, since this is rather distant from that event. On the other hand, it did manage to move the ground in New Mexico by a centimeter.

That still doesn't explain why the USS San Francisco's various sonars and sensors wouldn't notice a new geological upthrust.