They called it an "aquafoil," actually. Hydrofoils are REAL!
BTW, did the movie ever address the question of why anyone would want to live at the bottom of the ocean?
You got me!... I knew I should have double-checked Google! Thanks for the correction on 'aquafoil'.
Can't remember what was going on down there. Undersea mining? It did seem a bit more comfy than living & working on those Gulf of Mexico oil rigs, I guess....