Voyage to the Bottom of the Sea was one of my favorite programs as a kid during the 60s, and definitely one of the highlights of the week.
Watching it again now - 40 Years later - the sets and effects are mediocre, the continuity is occasionally poor to none existent, BUT... it's still very watchable and has certainly stood the test of time!
Recent 'Sci-Fi' TV series often seem to have very weak, drawn-out storylines more like soaps with an occasional hint of sci-fi, and rely on CGI graphical effects to try & keep some audience interest.
Voyage to the Bottom of the Sea is just the opposite of these: The stories are generally well written and self contained with a decent amount of action and suspense.
The actors are pretty good & their characters work well in the stories.
The end result is episodes which mostly rate somewhere from Good to edge-of-the-seat Gripping.