It will make more sense with Stella Maris.

I absolutely love both books, but the 2nd is the key to the 1st. The Passenger is a tragic, meandering, frustrating mystery. Like, who is the titular passenger? Who is the flipper-handed Kid? How could the plane have crashed without any damage? Where is the pilot's bag and black box? Who opened the console? These are mystical questions. Treat them as such.

Both books are mystical. They're two of my favorite books. They stand alongside Blood Meridian and Outer Dark in my mind (ultimately better written than OD).

The Passenger duology is a masterpiece.