New some spoiler help

[Gatts]

1) For the Kraken - there is on the same map a pirate with whom you need to speak after Mirabella tells you that she only marry you when you will defeat Kraken (she will tell you the name of this Pirate and his location) He will take you to Kraken - this may be little bit time consuming and also buggy (when I accidentally went in his way as I was bored, he stopped and needed like 3 minutes to start moving again)

2) I think it is the HELL (hence the part that is accessible by land from the first start point) ... but I am not sure...

3) I thought that the only ways are out to the dragon maze, than to other two isles, then under the life tree and two ways to the UDNEAD LAND (what should be actually the "underground"...) so I can't remember other underground... so I missed this as well (I know that I didn't finish the black unicorn quest was always to much in hurry and the reward was like nothing...)