The green inside the river circle are thorn bushes, 20 feet high. It takes 1 turn to clear a path 5 feet by 10 feet. A silver axe does twice as much.
There is a 2 in 20 chance every 3 turns that d6 basilisks are encountered: AC4, HD6+1, hp 31, 27, 34, 37, At 1 bite+gaze, D 1-10+petrification, save F6, N. On a gaze, save vs. stone to avoid the gaze, and be at -4 to hit and +2 to be hit; this is only a -1 to hit if a mirror is used; and a 2 in 6 chance it sees itself in the mirror. There are 75 total basilisks.