Crawl along the ground by using the left and right cursor (arrow) keys. This will not cost you energy, but if you don't catch fish, you'll lose energy gradually.
push yourself up with the "up" cursor (arrow) key, to catch fish. As long as you move upwards or fall back down, you can't move horizontally. Each jump costs a certain amount of energy. The higher you jump, the more energy will be consumed.
Catch as many fish as you can to gain points and to fill up your energy.
The higher up and the faster a fish is, the more energy and points you get.
Fish with a "-" (minus) on them, will suck up energy and give no points.
If you get in contact with a jellyfish or a ray (on the ground) you'll lose energy as well.
The game is over, when you have no energy left.