noun, な adjective, の adjective
The most deep is the deepest.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
Japan's deepest subway line is the Oedo line, which goes as low as 48 meters below ground.
Jealousy is the deepest sin of human sins.
Salmon and I had our wedding ceremony in a romantic hidden cave located at the deepest part of the ocean that light can still reach.