I know but I ignore the obvious most times.

Check out this NPR story...

http://www.npr.org/2016/02/22/467210492/u-s-navy-brings-back-navigation-by-the-stars-for-officers

I've never been trained on determining ones position using just a sextant and a clock, but I'm given to understand that it builds character.

There is already a thread on this: Old Tech is New Again

I had a course on it in NROTC but being far inland we didn't take sightings. Net result was that we could recognize a sextant and knew that one needed a really thick book of numbers to go with it - and an accurate clock.

Later, once aboard ship, the only contact with the sextant was to know where it was kept and maybe be invited to help inventory it once a year.

Navy Navsat was the predecessor to GPS and it worked faster and more easily than celestial nav - especially for a submarine.

GPS is near magical now. But can be turned off at any time. So old school skills could prove useful.
Still, taking sightings from a submerged submarine???? I hope not.

I'd have thought using a periscope for celestial sightings would be fairly straight forward. Just another sign of how reliant we have become on "tech" and more justification to bring back celestial.

For starters- Scope course is parallel to the waves so you don't get sucked up and broach. In a round bottom boat.

There might have been special scopes for early boats but I've spent a lot of time dancing with the one-eyed lady and it's difficult to keep a contact in sight nevermind getting a precise elevation angle.....

Probably WWII boats used celestial but they would have a sextant because they were really just surface craft that could disappear for awhile.

I can recall reading some documentary about WWII subs. They indeed surfaced often to take celestial bearings. Now they just surfacing a tiny floating antenna on a cable. However, with the modern tech it's not that hard to implement either a gyroscopic sighting aid integrated in the periscope, or even a completely computerized celestial navigation system similar to those pinpointing the spacecrafts precise landing after years of navigating in space. By the way, Mars rovers were using celestial navigation for their ground operations long before the nav-sats started orbiting Mars. They still do actually, as the MGPS constellation is not thick enough yet.

They used a sextant as the alternatives where even less accurate when there was no landmark in sight. The subs surfaced to use the sextant. That was some disadvantage especially after the allied forces became better hunting them.
That´s also featured in the movie "Das Boot". Two submarines met in a storm and the skippers come to the conclusion that they are nowhere near the coordinates they were supposed to be. The reason was a longer period of bad weather which did not allow to get a fix with the sextant.