Use the arrow key to move Nemo. The space bar to jump. Help him reach his working depth for each level (listed on the left side of the screen) and then climb back to the boat to complete that level.
You can pick up tools (wrench) to score points and look for power-ups that heal Nemo if he has been hurt.
You'll need to avoid the sealife as it can hurt Nemo and cause him to plummet to the depths. If he goes below the assigned working depth you'll start to lose points so hurry back up.
If Nemo spends too long at depth you'll need to stop for decompression at 60 feet before returning to the surface.
-Watch for alerts on your dive monitor(left side of screen) and the big decompression bar that appears when you reach 60 feet, if decompression is required.
If Nemo goes up before he is decompressed, he may suffer injury. So be careful!