Claustrophobia - a fear of being in closed or small spaces or an unhappy or uncomfortable feeling caused by being in a situation that limits or restricts you. More than likely you will not encounter claustrophobic conditions on the ship. It would only occur in catastrophic situations like the ship rolling over after being hit by a Tsunami like in the movie the "The Poseidon Adventure"-
a fictional shipwreck tale. The 'Poseidon' was capsized by a Tsunami, and a handful of survivors trapped in airpockets try to make it to the propellor shaft where the hull is thinnest. They were challenged with the task of getting through flooded portals which would have challenged the most claustrophobic-resistant person.
Bringing the problem to a more realistic level, I think the possiblities of claustrophobic attack are more possible on a shore excursion. The person who is cluastrophobic will generally know themselves, but they will not always know when the conditions for an attack will occur. I have witnessed a man in Puerto Rico suffer a case of claustrophobia while he was descending a set of circular stairs with a very low ceiling. I also saw this occur on the submarine at Baltimore Harbor when a woman had a claustrophobic attack during a tour of the sub.
I can only say that persons who might be subject to these attacks, should think twice about some activities like: Submarine rides, cave raft floats, cave exploring.
Don't let claustrophobia mess up your cruise.