My MIL went on this excursion. She tends to worry about claustrophobia, but she had no problems with this. Except when you're in the viewing room, the boat feels like a boat... not like a tin can held under the water. When it's time for the viewing, you go downstairs to the viewing room, which is below the water line. Chances are you'll be so enchanted with what you see, you'll be too distracted to worry about your phobias.