In the case of aircraft, since e-cigarettes and other vaping devices use high discharge lithium batteries, they must be taken on board in carry-ons, not in checked luggage.
These batteries are susceptible to overheating to the point where they can ignite. If that happens in the hold it is not possible to fight the fire, and the outcome could be catastrophic.
Smoking an e-cigarette on an aircraft is strictly forbidden.
On a cruise ship, regulations regarding e-cigarettes vary from one line to another but all cruise vessels have designated smoking areas.
European lines are slightly more liberal, but most forbid smoking in cabins, and only a few allow it on cabin balconies.
There are some exceptions, such as Holland America Line, which allows e-cigarettes and other vaping devices inside staterooms but not on stateroom verandahs.
Smoking of e-cigarettes is also allowed in guest suites on Seabourn ships and in some cases on private verandahs.
Anyone caught smoking in their cabin or on their balcony when it's forbidden might face a cleaning fee, usually in the vicinity of $250.