Q:
Getting to the Cathedral of Silence
How did you fail? If you expect any help you need to be clear why you failed because the route very straight foward
If I’m thinking of the correct mission, the entrance is easily found via
the Penitent Path waypoint. Enter the river from there and swim south. At the end, you go underwater and you will find the cave where you'll need to be.
If I’m thinking of the correct mission
I think your description matches the mission afterwards. Anyway, I’d agree we need a bit more detail about why the OP is having difficulties. If it’s just that you are getting killed the way to the CoS, your best bet is to keep map chat on and look out for comments like ‘Grenth up’ then follow the zerg to that area.
May I just say – thank you thank you thank you. If people like u didn’t take the time to post these helpful hints – I’d never finish the game. Mucho appreciation.