Bowser's Lava Lair
Bowser's Lava Lair is a galaxy appearing in Super Mario Galaxy 2, being the final galaxy of World 2. The galaxy is abundant in lava, hence its name. Whomps are also present in this galaxy. Giant Bowser is fought here for the first time, and upon defeat, awards a Grand Star.
NOTE: Unless otherwise noted, all names are unofficial.
A simple planet with a few columns on the sides and a Magikoopa that spawns Li'l Cinders with its magic. There is also a Luma that tells Mario that it senses a Grand Star ahead. It also warns Mario that there is danger ahead.
Very similar to the Cylindrical Planet, but with differently moving platforms and several fireballs spinning rapidly on the sides of it. A 1-Up Mushroom and a Life Mushroom can be found on this planet. At the top is a Crystal with a Launch Star inside that leads to the first Lava Planet.
Whomp Lava Planet
A very large planet with surrounded by lava. The Toad Brigade and a Tip Network is found here. Mario will also encounter some Flomps that spin to throw Mario backwards. After defeating a few Hammer Bros. on a circular platform a Sling Star will appear. That leads to a short tower with a platform next to it. The platform has a ground-pound switch and leads to the lower lever of the planet. The player will encounter more Flomps. Whomps and Dry Bones are also found here. He will also find a door with a big stone lock which he must break by ground-pounding meteorites.
Lava Cube Planet
A rather small planet compared to the last one. Also surrounded by lava, there are some Mattermouths. There is a black hole inside this planet. Near the Checkpoint Flag at the beginning one of the members of the Toad Brigade trying to find a 1-Up for Mario gives him some Star Bits. There is a Snake Block that Mario has to stay on in order to get across the lava. Another Life Mushroom can be found above the Fire Bars. Then there is a another, smaller, Snake Block. This time Mario has to avoid electricity-shooting Bowser statues, somewhat similar to the ones in Super Mario Bros. 3. Before the final Checkpoint Flag are three Hammer Bros. After getting past that part, the player must break three stone locks to open the door to go battle Bowser. There is yet another Life Mushroom above one of the flagpoles. If playing the mission "Lava Lair Speed Run", the player has to make it behind the giant door to get the Power Star.
A small planet shaped like a star. In front of it is another planet shaped like Bowser's throne. After talking to Bowser, Mario will be sent to the Bowser Battle Planet. Mario and Luigi cannot lose a life on the star-shaped planet, rather, if they jumped off the side of it, they would be surrounded by energy and carried back onto the planet, like they would when falling off the Comet Observatory in Super Mario Galaxy.
Bowser Battle Planet
It is a small planet resembling a castle made of black bricks and a few rocks that Mario can break to get coins. Here, he will battle Bowser by ground-pounding meteorites at him.
Green Star 1
This Green Star is located on the Lava Planet. To get it, Mario must go to the platform with a stone switch on it. Then, long jump to the left by a rock and grab the Green Star behind it.
Green Star 2
This star is located on the second Lava Planet, under the stone area. Mario must wait until a Mattermouth eats a part of the platform under which the star is. He must fall carefully to grab it.
Prima Official Game Guide description
Names in other languages