Naples

terri, IMHO, it will be very challenging to see all three of those locations in one day. When you specified that you'd be "arriving by boat", I assume you're referring to a shore excursion from a cruise ship? Getting to Pompeii from Naples is relatively easy. You'll need to get from the docks to Napoli Centrale, go to the lower level and take the Circumvesuviana train to Pompeii. When you reach the ticket booths at Pompeii, you'll probably be approached by local Guides offering their services. If you'd like to pre-arrange a Guide, Gaetano Manfredi is outstanding! Getting to Mount Vesuvius is going to be a bit more difficult. As I recall, that will involve a Bus trip to the Base of the trail (it's a very winding road, so hopefully you don't suffer from motion sickness). The hike to the top will take at least 30-minutes, depending on your hiking ability. The Museum you're referring to is the Archeological Museum in Naples. That will probably require at least two hours to go through. If you'd like a local Guide for the Museum, check the Guidebook for listings. You'll need to add transportation and waiting times to each of the trips, and that's why I'm not sure it will be possible to see all three in one day. While it might be feasible, most of your time would be spent in transportation and you'd have little time for actually seeing each of the destinations. If you're planning to use Taxi's in Naples, be sure to read the "caveats" in the Guidebook. Happy travels!

Terri:
Walks of Italy does a Pompeii and Naples Arch. Museum tour of 5.5 hours. We tooks their "Pristine Sistine" tour of the Vatican and were very pleased, so I am considering them for a future trip to Pompeii. Worth checking them out at www.walksofitaly.com. A guided tour, while carrying a pricetag, can save you a lot of time, which is precious. It's important, IMHO, to find out how many people will be on the tour with you. If the group is too large, it loses personal value and you end up on a forced march. You can arrange private tours with Walks of Italy and with other guides such as the mentioned Gaetano Manfredi. If this is a really important area for you, I'd encourage you to hire a private guide/arrange a private tour and make them most of your limited time.

Arriving by "boat", do you mean ship? If so, the cruise company will probably have planned excursions. By exploring on your own and not knowing travel times, you run the risk of not getting back to the ship on time. Your one-day bucket list is a little ambitious. Pompeii is a large place and will easily eat up half a day on it's own. You will probably have to eliminate one thing from your wish list.

Some people prefer to do the tradeoff of visiting Herculaneum instead of Pompeii. It saves you lots of time because it's a much smaller site and it's closer to Naples. You can do it and the archeological museum in one day. But do consider the tour organized on your ship. Although pricey, they will ensure that your time is spent efficiently and that you make it back to the ship in time.