Hi I need help on how to get down to the Lost city, colleseum and also there is a quest i must go and find a no-dache
"sword or somethin" its in a sacred stone??, but how do you find the entrance to the lost city, i hahe read that i need some sort of breating masks...???

The No-Dachi is near the isle of sands (pyramid area).

Yes, you will need breathing masks for all of your characters to survive in the underwater city. It's located offshore in the Lost Sea a ways north of the shoreline entrance to the trail to the pyramid.

Start looking for and fighting CRABS - collect their shells and return those to the the shipwright in Brimloch Roon. He will make helms and rebreathers for you!

I found the best way to locate crabs was to sail around near the short (except near Talrik the Pirate) and wait for my scout to tell me crabs had been here. Jump off the boat and look for them.

Wyv