caves space

   0   1   2   3   4   5 

5 glen         +---+---+  5
   |           |       |
   |           |  mnt  |
4  +---+---+---+   +   +  4
   |       |       |   |
   |       |       |   |
3  +---+---+   A---+---+  3   
       |   |       |   |
       |   |       |   |
2  L---+   B   Y---+---o  2
   |   |               |
   |   |               |
1  +---+---Y        coast 1
       |    
       |        
0  Y---+                  0

   0   1   2   3   4   5 

mnt = exit to mountains
coast = coast
o = cavern exit to coast
L = cavern elbow
A = cavern dead end
B = cavern dead end
Y = forked dead end
glen = exit to glen