(Kho) Phi Phi Island is in what is called the Andaman Sea, part of the Eastern Indian Ocean and separated from the bay of Bengali by the Andaman and Nicobar Islands.
You get to the island on a ferry from either Krabi (about 90 min) to the East or Phuket (about 2 hrs) to the West.
Once you arrive you need to pay the fee for entry into the national park area, payable by csh – it is currently August 2018 THB 400 for foreigners, add another THB 200 if you plan on going diving in the waters off the islands.
Once on the island, it is really up to you to decide which Phi Phi you prefer, wild ride or tranquility. If you chose to stay in “town”, that is by the ferry landing – it will likely be on the wilder side of things. The little town is bustling with bars, restaurants and other places of activity. However, if you prefer the tranquility part you may want to stay a little bit out from the ferry landing, just remember that you are pretty much at the mercy of the long tail boats for transportation into town.
There are no cars or really no motorized vehicles allowed, there are a few utility vehicles and there are also some “law-breakers” that have scooters, but not many. You can walk, but I can not recommend it and especially not if you have been in town imbibing, the walk is pretty long and at times treacherous. The long tail boats run most of the time, but there are exceptions, such as at low tide and with too high surf, they may not run, the captains are very much adverse to taking any risks with their boats so if the tide is too low or the surf too high you will have a hard time talking them into making the trip, offering better pay of course may help – standard fare somewhere between 100-200 THB (Thai Baht) each way ($3-6 USD) some of the resorts located further out on the island also may offer some boat services that are included.