Do New York City subways travel underwater?

Answer 1

I assume you are asking if the subway tunnels go under rivers or oceans. The answer is yes. For example, the NYC subway goes to Brooklyn and Queens, which is on the opposite site of the East river from Manhattan.

Answer 2

No, they don't. The Hudson River runs between New York City and New Jersey (specifically, it runs between the east side of New Jersey and the west side of Manhattan and the Bronx). New York City subways do not go to New Jersey, hence, none of the subway lines run under the Hudson River.

Several subway lines run under the East River, however. The East River runs between the east side of Manhattan and the Bronx, and the west side of Queens and Brooklyn. Several subway lines run between Manhattan and Brooklyn/Queens, and some of them run under the East River.

Answer 3

Yes, that is why they are called "sub" ways. The prefix sub way means under.