The same goes for train travel and car travel but there is an exception for travel by boat: if you travel by ocean liner, cruise ship, or other form of luxury water transportation for business purposes, there is a daily limit on the amount you can deduct.
The capability to severely disrupt America's C4ISR network, coupled with the deployment of advanced submarines and anti-ship missiles, presents a new form of strategic deterrence that is only recently receiving the attention it deserves.