There are two primary ways to visit Petra. The most user friendly is via Amman, the capital city of Jordan. Simply take a service taxi from the city center down to Wadi Mousa. This should be no more than about $20JD ($28US) and the ride takes about 3 hours over excellent roads. This works, though, only if you're arrived in Amman by air or bus from another country.
The way WE did it was as an excursion from the Sinai peninsula on our trip to Egypt. If you are in Egypt, you are TOO close to Petra to find an excuse NOT to visit here. It is simply a life-changing experience, if done properly.
With that in mind, find your way to the Egyptian Red Sea port city of Nuweiba. It is easily and cheaply accessed by bus via Cairo or Sharm el Sheik or Dahab. Or if you have a rental car (brave, brave soul) just drive there and park at the port.
IMPORTANT: You need to do a few things before entering the port.
1. Visit the bank in Nuweiba and purchase an Egyptian visa stamp ($15US), but don't stick it in your passport! Keep it safe somewhere else.
2. Go to either the Hilton Nuweiba (ask anyone for directions) or go on the road that heads south of the port to the boat company's office to buy your ticket. Make sure you purchase your ticket on the FAST BOAT. Trust me, you don't want to take the slow boat, and it's only a few dollars cheaper.
This ticket is expensive by Egyptian standards. It is $45US ONE WAY and can ONLY be paid in US dollars (go figure!) so make sure you have US currency available. If not, you'll have to change money at the bank in Nuweiba.
Once you have ticket and visa secured, head to the port and enter the chaos.
The ferry departs Nuweiba at 3pm, but you MUST BE AT THE PORT to check in by 1pm or you'll simply never make it.
There's no way I can guide you through all the steps of getting checked in. Just ask any uniformed man and they will escort you to the front of each line (unfair to the locals, but they understand what your money means for the country) as you go through customs, immigration, and checkin. Then, find a place to sit or stand amongst the masses of sleeping men, crying children, and women holding 12 chickens inside the main port barn.
Eventually, the guards will shout several things in Arabic and people will start to line up and get on buses. Usually they load the slow boat first, and usually (since Westerners always take the speed boat) they announce boarding for the catamaran as "FAST BOAT" or "SPEED BOAT" in English as well as Arabic. You'll be herded onto a bus and taken to the catamaran where you'll form a single file line to board the boat.
The boat is clean and comfortable, and you can change currency on board, as well as buy snacks. The ride from Nuwieba to the Jordanian port of Aqaba takes an hour.
Upon arrival in Aqaba, you'll exit the boat and endure the unnerving experience of handing your passport over to a smiling immigration officer who tosses it into a bag with everyone else's. Then you'll walk up into the arrival lounge and wait.
Your name will be called, likely before the Arabic people, and you'll go up to the counter to pay for your visa (less than $10US paid in dollars or dinars, and you can head past immigration and change money if you need to). They will place the large immigration stamp in your passport and you head through the terminal and through customs (a breeze if you're a Westerner) and into the open at the mercy of the cab drivers.
Don't leave your bargaining skills behind in Egypt. These drivers will ask you for $50JD to take you to Petra. The going rate in 2002 was actually $30JD, lower if you're a hard bargainer, so don't get ripped off.
The journey takes an hour and half, and will be in the dark if you came in on the ferry. The roads are excellent, though they get a bit scary when you enter the mountains near Petra.
The driver will likely want to take you to a hotel where he recieves a commission. DON'T LET HIM! Tell him you want to go STRAIGHT to Valentine's (if he doesn't know Valentine's, call it Twaissi and he'll know the place) and he'll take you there. Valentine doesn't pay commission but they do treat cabbies well and usually feed them dinner. Don't forget to tip him a few JD as well.
If Valentine's is full, ask her for a recommendation and your cabbie will take you there at no extra charge.
To return to Aqaba, there is a much cheaper alternative. Shuttle buses depart RIGHT from Valentine's front door early each morning and cost only $2JD per person. The only reason you can't take one of these cheapies from Aqaba TO Petra is that the ferry arrives long after they leave. Just make sure to tell Valentine the night before that you'll need the bus and she'll make sure it's there for you. Also check with here on the time the ferry departs. It's usually around 10am.
The bus drops you off at a central station in Aqaba, and from there you can grab a cab for $3-$5JD to take you for a spot of breakfast, to the boat ticket office to get your tickets, and then to the port.
If you forgot to buy your visa stamp back in Nuweiba before you left, have your cabbie take you to the Egyptian embassy, as well, and buy your visa stamp. DO NOT WAIT UNTIL YOU GET TO NUWIEBA or you'll be in trouble.
Your ferry ticket back to Nuweiba is cheaper on this side! More like $20US instead of the $45 you shelled out to get here. Also, you can pay for your tickets in dinars, you don't have to have U.S. dollars. You'll also pay a modest departure tax (about $5US).
After arrival in Nuweiba, the typical Egyptian chaos takes over, thrusting your heavenly memories of civilized Jordan back into your skull somewhere dark. If you don't have a visa stamp to put in your passport, you'll endure UTTER HELL trying to secure one. I'll spare you the details, but take it from firsthand experience...spend the extra 5 minutes and get it before you leave.
After immigration, you'll be buses to the arrival barn, where you'll grab your bags (if you checked them, but don't), they'll be x-rayed, and then you'll be searched for customs. As long as you don't have a video camera or a laptop, you're fine. Otherwise you'll be charged a hefty import tax.
Then you'll have the joy of sitting at the locked port gate until each passenger on the list has been manually checked against a blacklist of terrorists and criminals, and about 3 hours after your boat arrives you'll FINALLY be free of the port.
To save lots of bureacracy, it is ideal to arrange your Petra visit at the END of your Egypt visit, and have your airline ticket to fly out from Amman, instead of subjecting yourself to the torture of returning to Egypt. Or you can continue from Wadi Mousa to Isreal, via Amman. It's practically pennies by bus.