Densetsu no Yuusha no Densetsu: Legendary Saga

Since I can't read japan so I play this game random so far but now I stuck can some one tell me
1. how to walk across the water
2. what to do next after to I reach to dungeon B5 (second dungeon after to go in to next castle) that have many strong monster like big lion big wolf (Sorry I can't write dungeon name cause I can't read it) because I walk every area on this floor but I can't find where to go next.

sorry for bad english thx