The motor of your ship is broken. Go in search of parts under water so that you can build a new motor! You can only build close to your ship or to a workbench. Combine the right items: you can find these combinations under 'recipes'. If you want to dive deep, you'll first have to build things like a like a workbench, an oxygen cabinet and a lamp. Keep an eye on your battery, your oxygen level and the pressure on your diving gear. You can upgrade your laser, your lamp, your diving gear, your oxygen level and your boots.
WASD or arrow keys = move around,
1-6 = select an item,
Click = use selected item,
F = flashlight,
E = use building (e.g. workbench),
Q = open inventory,
R = show recipes,
H = show game instructions.