chinese submarine crew poisoned

Hydrogen sulphide only has an odour at low concentrations. At higher concentrations it is odourless. I think one of the first things it does is burn or kill the odour receptors in your nose. This is why confined space entry (Manholes, sewers) must always use a gas meter, not a sniff test.

What a great honour for those 55 sailors to be able to die for the motherland.