An Ocean Planet is a type of planet that has a substantial fraction of its mass made of water. The surface on such planets would be completely covered with an ocean of water hundreds of kilometers deep, much deeper than the oceans of Earth.
Acid Planets have thick atmospheres of deadly gases like Carbon Dioxide, Cyanide, Nitrogen Dioxide or Sulphur Dioxide.
A Gas Giant is a giant planet composed mainly of hydrogen and helium. Jupiter and Saturn are the Solar System's gas giants.
An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two known ice giants in the Solar System, Uranus and Neptune.
A Chthonian Planet is a class of celestial objects resulting from the stripping away of a gas giant’s hydrogen and helium atmosphere and outer layers, which is called hydrodynamic escape.