Turns out, we might be safer if we never leave the city. Ever. Well sort of. A new study based on an analysis done by the Port Authority of New York and New Jersey found that train tunnels under the Hudson River are more vulnerable to a bomb attack than previously thought. Apparently, it would only take a fairly small amount of high explosives to cause major flooding of the rail system, explains The New York Times. The analysis shows that in less than the time it takes for your morning shower (depending on what you do in there), the tunnels could flood.