To start driving, you have to wait, until it is loaded and then activate the applet by clicking it with your mouse pointer. Then you may use the following keys to control it:
CURSOR LEFT: drive left CURSOR RIGHT: drive right CURSOR DOWN: dive (in water) CURSOR UP: float to surface (in water) s: rotate turret contra-clockwise f: rotate turret clockwise d: fire the "rope" using the turret; press again to "cut" the rope e: shorten the rope (pull) c: lengthen the rope 1: switch to rope #1 2: switch to rope #2
There are two grappling hooks (key 1 and 2 to switch) - if you use them together, you can get almost everywhere. Trying to go through the level with only one grappling hook might be a bit tricky.