This is one of the rare bad sci-fi movies that I actually stopped watching before it was over! The best thing can say about this film is that for the first 20 minutes or so, I didn't realize that I was watching a made-for-TV movie. The initial scenes seemed hokey, but the acting, sets and story were engaging enough, including an attack on a ship and the introduction of Dr. Arronax and his daughter.
But the film sprung a leak as soon as we get to the Nautilus, and the results of a small fx budget start to really stand out: uniforms that looked like my mom sewed them for the class play, tons of stock footage of the same coral reef going by the porthole endlessly, a night scene where I could swear they used lightbulbs to simulate stars in the sky, and finally (when I gave up watching), an incredibly silly and fake-looking sea monster.
The effects were not the only disappointment - nobody in this disaster at sea could act either. Please, watch the Disney version with James Mason and Kirk Douglas instead. Still silly, but well done.