Professor Raile Shaia is the decendent of Lexis Shaia, the genius inventor who helped Maxim and his party defeat the Sinistrals. Like Lexis, Raile is a genius, but he is also quite eccentric. His inventions never look very stable, but they ended up being very reliable. He first gives the party a Ship, and then a Submarine, and finally an Airship. The name of this extraodinary vessel is Falcon. You have to spend what seems like Half the game tracking Professor Shaia down, traversing several continents, at least 3 of his many labs, and several towers and caves where he was "last seen".
Getting the Submarine and Airship vessels, however, are just as different. For the submarine, you have to gather seven pieces of a material called "Alumina", and in order to do this you have to search 3 caves. You still wont have enough, however, and have to satisfy the taste of a VERY picky king before he will give you some of his collection. Then, when you have everything you need, the Professor's son, Lou, is kidnapped by pirates. Raile tries to save him, but is captured as well, and it is up to you to defeat the rather tough pirates.
In order to get the Airship Falcon, you have to get something called "Power Oil". This wouldnt be so hard if only you could GET to the cave easily The cave it is found in is rather easy, but is very remote. It took me quite a while to trailblaze a path to it, so good luck. The boss is not very tough as long as you are leveled-up enough, and have fire resistance.