Underwater cameras only work up to a certain depth. You cant just mount a camera on the outside of a submarine. The submarine would need to be made to accommodate a camera filming the exterior, and in this case it doesnt appear to be.
But I agree that these guys seem like actors, and dont seem to have much to say.
Well it is a made up thing so yah
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You wouldn't want to see my tank. I don't use fancy equipment and I am a noob