quest -> teleport to warlock cave
Raft movement
Arghhh, you guys got me.. So there are 7-SEVEN ways to cross the river..
Any more??
Beating Eagle King and/or Lord of Darkness (latter dependant) are also ways to the Middle Region. But if we're talking direct space -> space river crossing, then I would discount Warlock's Quest. If just about getting to the Middle Region (which seems to be the case since Adventure cards like Rune Gate and Imp are probably in that 18 cards you mention), then we're up to 8/9 ways.
A few characters start in the Middle Region, not sure if you want to add that method to your list.
I think that if anyone notices the way to get across the sliver of a space, then power to them. Like the quote that JCHendee quoted, any of the space directly across, reads any space to me, so they would have found a secret little fork in the river that lead them to that space
I guess for the purpose original question (which spaces can one land upon), the only relevant options would be:
*Raft from axe(forest and two woods spaces)
*Spell-Water walk (Any space)
*Raft from Market day (Any space)
*Raft from Encounter card (Any space)
So in brevity it comes back to raft and the rare spell of water walking
I still feel it should be only one space to enter, but rules are rules in this case