Remember seeing this at school in the late 70's, so it was made before then. Thought it was good, but was many years ago and I was young. Was one of those Journey to the center of the Earth type movies. Had a large diving bell that went down in the water and surfaced in an inner Earth world. Was in Color (not colorized)
Think I remember the movie poster had a color drawing of a couple of dinosaurs walking up the side of a cliff or wall.
Wish I had more. Tried looking at IMDB, there seem so many of that genre.

The Beast from 20,000 Fathoms?

Hmmm, a color pre-1980 "prehistoric world beneath the earth" movie. A couple come to mind, but the bit about the diving bell and going through the ocean throws me. "At the Earth's Core" and "The Last Dinosaur" comes to mind, but in both of them they travel in a burrowing machine, not a diving bell.

The Land That Time Forgot (1975), maybe. There was a sequel too in 1977, "The People That Time Forgot".

I think I know exactly the movie you are talking about, but I don't recall the title. I don't think it was either of the two mentioned above. If it is the same movie, it had a bell capsule just like a metal upside down fishbowl with an open bottom, it was launched from a surface ship and may have even had an airhose. I'm going to take a look around IMDB.

Could it be "Warlords of Atlantis" (1978)?

Wmansir,
Yes, that rings a bell (pun intended)! Is it Warlords of Atlantis?

It's definately 'Warlords of Atlantis' - one of Doug McClure's 'classics'

it doesn't appear to be so, tho. from the poster there, it would appear the diving apparatus contradicts the OP's description of a bell-like ship.

however, the description of the plot in part sounds awfully like disney's atlantis. so perhaps this movie does involve atlantis in someway (clearly not disney's, but an atlantis-like story)

who knows. i know i've not seen it.

Doug McClure certainly seemed to be the "go to" guy for cheesy 70s lost world movies. He must have had a prior commitment that prevented him from being in "The Last Dinosaur".

Yes, I'm sure it's Warlords of Atlantis, but the movie poster I remember then might be from another movie of the same genre. Does anyone recongnize the movie poster that showed approx. two dinosaurs walking up the side of a cliff or wall twords people above. I specifically remember that it looked like these dinosaurs (I think four legged ones) appeared to be defying gravity because it appeared that they where walking up vertically like someone had drawn two dinosaurs walking on land then turned the drawing on it's side to make them appear going upwards. I think this was from a scene near the climax.

Well, I should know if they are both the same movie soon, ordered Warlords of Atlantis DVD from Amazon.co.uk

Yes, this was the one and yes it has two "creatures" that resemble dinosaurs walking up walls. Enjoyable flick for what it is, but not nearly as good as when you first see it young. But I guess that's how most are. Story seemed very absent now that I'm older...