The cargo hold stands for what is stored below the surface — memories, burdens and things you carry without looking at them. Dream books read exploring it as facing what has been packed away.
Where in your waking life have you met something like this lately?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.