So this is what they chose to open the third season of Voyage to the Bottom of the Sea with? Fortunately there were enough positive factors to out-way questionable concept.
Let's see, this was the third season premier of the three Irwin Allen series that year.
You had season two of Lost In Space, with 'Blast Off Into Space' on 14 September 1966 (the first season to be in color), and the premier of The Time Tunnel on 9 September 1966, then this episode on 18 September 1966.
And this unknown show on NBC, Star Trek, with 'Man Trap', on 8 September 1966, and 'Charlie X' on 15 September 1966.
It was a great time to be a science fiction fan for TV.
As for Dick Tufeld, he was very busy, doing the Robot on Lost In Space, and narration on The Time Tunnel, and then this episode.
The fast pace and the actors, as well as the voice of Dick Tufeld are what make this episode watchable.
In too many other ways it falls short.
For example, when the Seaview hits the bottom of the ocean, there is almost no dirt stirred up.
And they needed the nuclear reactor to get off the bottom of the ocean? It is a submarine. You want to go up, you blow the ballast. You only need enough power to run the pumps.
Speaking of nuclear reactors, while I do not know the control mechanism used on real-life nuclear submarines, manually-operated rods do not make a lot of sense.