A couple of minor issues I tripped over due to experience with other text adventures:
- Consider adding the standard text adventure shortcut commands: "x" or "examine" for "look at", and "i" for "inventory".
- I found it surprising that "look at inventory_item" didn't work. "look at boat" or "look at vest", for instance.
- How about "help command" for each command listed in the "help" output?