Cheat mode - Japanese version 
At the title screen, hold L1 + Select and press Triangle to access 
a cheat menu that enables level select and invincibility. After 
using the level select option to choose a level, press Triangle 
to exit the option screen. Then, start a new game to begin on the 
selected level. 

Underwater lightsaber 
It is possible to take out your lightsaber while underwater. Press 
Start, highlight "Weapons" and select the lightsaber.