To the grotto~

[RinnosukeKourin]

Hello~ Rinno here~ I need some help, my current main quest is the undersea cave and I have a hard time completing it, (took me 25 min to get have way only to die and have to restart), I'm trying to get to the grotto in echigo, anyone will help. Please and thank you!
(ign:RinnosukeKourin lvl:66 Type:bow user)

[Momiji]

I require assistance clearing Sado cave as well, any high level willing to help?