I've played this game before but never had ths problem. I'm in the underwater observatory, trying to get a submarine to go exploring. I've charged the claw time and again but the sub won't show up. What now?

Have you gotten the message for starting this challenge yet? The subs won't be there until you get this message.

Otherwise, it has been too many years since I have played this game to remember all of the details. All I can suggest, I'm afraid, is to take a look at a written and video walkthrough if you haven't already.

I went out of the challenge and then came back and the sub was there. Go figure.

Whatever works!