Sphere map? *SPOILERS*

Hello, I am planning on re-reading Sphere (it's been years since my first reading). I remember not having any sort of mental image of the underwater station with all the numbered and lettered rooms and their connections. It seemed very confusing as some rooms became flooded and unusable, and when he was stuck outside how much of danger he was in when trying to find the entrance. Is there any map of the underwater base available? Official or fanmade? I feel being able to look at a reference would make it much more easily understandable.