Not bad, but call me when it's a submarine with Raquel Welch on board.
https://www.youtube.com/watch?v=AmNTFlRASYY (Fantastic Voyage, 1966)
https://www.youtube.com/watch?v=AmNTFlRASYY (Fantastic Voyage, 1966)
Do you remember whether in the movie they explained why they can see outside the ship?
I don't remember if they tried to explain any of the "science" - rather doubt it. Maybe blood is clear between the red blood cells? Guess they had good lights on the sub too.
Flesh Gordon (campy porn version of Flash Gordon) is another recommended movie with similarly awful special effects !
The original book by Isaac Asimov probably had pretty accurate biology. Don't know how much the movie changed it.