They are Navy, they can't be scared to go somewhere because they have no charts. Also this might have been on Chinese territory so maybe that is a reason for mi

They are Navy, they can't be scared to go somewhere because they have no charts. Also this might have been on Chinese territory so maybe that is a reason for missing charts. Or maybe they had some mission that required them to go there. But that this doesn't mean there couldn't be precautions. I expect there is some procedure to use when running in those conditions. Knowing Navy, they have a procedure for everything. They can't be mapping ocean bottom by crashing nuclear subs into it until they have enough data points to build an accurate map. One of the axed people is a sonar guy. This suggests to me (keeping in mind I have no knowledge of submarine operations) that people responsible for the sonar were probably not doing what they should be doing. So maybe there is a procedure to use sonar to help them avoid obstacles. I don't know how this exactly works in an enemy territory.