Super Mario Galaxy/Deep Dark Galaxy

Deep Dark Galaxy is accessible from the Garden observation dome. You need 46 Stars to enter.

The main planet has a beach and an underwater section past a gate. There are also a couple of smaller planets.

Star 1: The Underground Ghost Ship
First you will need to jump into the cannon and fly to the brown planet (you will need to grab the star that makes you invincible to pass through more easily). Grab the Fire Mario and shoot back to where you started off, then quickly run and put fire on the two fire emblems so the gate will drop. Go down under into the lake. For the time being, ignore the shell you will find underwater, as that will lead to the Hidden Star 6. You will see an arrow made out of Star Bits. Follow it and destroy some boxes to twist the lever. The gate will open. Now swim up and again there will be another lever in the corner: twist it. Swim to the top to find a ship, climb on and you will meet the boss Kamella (from Kamella's airship attack.) Defeat her and get the star.

Star 2: Bubble Blastoff
When you first land on the island, you will see two toads hiding behind and umbrella. You may talk to them if you wish. They say that someone has hijacked the cannon. If you proceed beyond the umbrella, and Undergrunt Gunner is shooting bubbles at you via a cannon. There are two ways to beat him: 1. Jump on top of his cannon and ground pound into the glass three times or 2. Spinning the coconuts scattered about in his direction, again three times. Once the Undergrunt Gunner is gone, you can kill the crabs and collect the Star Bits hidden in the shells on the ground if you like. Then drop into the hole the cannon left, and you'll be loaded into a smaller cannon. Aim yourself towards the brown planet and the Rainbow Mario star that happenso to be in the path. This will make wiping out the Octoguys on this planet a breeze. If you missed it, there is a Fire Flower at the bottom of the planet, which you'll need to grab to light torches back on the island. Killing all the Octoguys gives you no special reward, just lots and lots of Star Bits. Use the Sling Star to return to the island. If you light all three torches before your Fire Power runs out, you'll be rewarded with an Ice Flower, which you need to climb the fountains later. Jump on the Magkoopa for a coin, and then skate across the lake. Don't mind the Toad on the beach, just jump on the jets of water to freeze them and use as platforms. Then grab the orange pole and climb to the top, but beware of the Octaguy at the top. Run to the edge where you see a line of Star Bits falling. Collect them while falling, and then climb up the orange pole. Swing on the pins to get across the pit. If it tickles your fancy, swing onto the lowest red platform, then jump to the upper platform to collect a ? Block. Then fall to the grass. Walk across the grass "bridge" to a floating platform and a Giant ? Coin. Collecting the coin causes the platform to turn into five Sling Stars. Shake to use them. They'll take you to a small grassy area. Jump onto the platform with the bubble machine, but don't take it quite yet. Go to the far right of it and past the two rocky spires. You'll come to a grassy arena with two Magikoopas. Defeating them is optional. Take the tube down. You'll come up in a room with bricks along the front wall and two Giant ? Coins. Collect the one on the bottom right first, which should create music notes. Collect all of them for a surprise. The second Giant ? Coin which is in the upper right turns all the bricks into Star Bits. Return to the grassy arena through the tube. Go back to the bubble blower you saw before, and stand on the brick in front of it. A bubble should hit you and give you a ride to the first yellow platform. Collect the circle of Star Bits there, and drop down to the lower left grassy platform with a second bubble blower. This time, however, you must stand on top of the blower to get a ride to the second yellow platform. Fall again to the left where you see two fire shooters. Avoid them and climb up the orange pole, but beware, there's a Magikoopa at the top. Defeat it and climb up the next orange pole. Now there will be a circular platform with a rotating row of fireballs and a bubble blower. Hitch a ride once more on the bubbles, this time, however, you'll be taken to a new small planet. Here there are Cheep-Cheeps. Defeat them if you like, but be sure to ground pound the three wood cylinders, which activate another bubble blower. Take one last bubble ride to a glass and gold planet. Here, you must ground pound on the balls inside to make them hit the watermelon, but beware of the lasers that circle the planet. Hit all three balls into the watermelon, and the planet becomes the watermelon. A Power Star will appear at the end of the planet, but watch out because the lasers still go. Collect the Power Star and you're done.

Star 3: Guppy and the Underground Lake
This star is pretty straightforward. Land on the Main Beach, and enter the gate to the cave containing the lake. Dive to the bottom of the lake and talk with your old pal Guppy. He'll challenge you to get through his rings if you want him out of the lake. Accept and follow him through the rings. Pick up the Green Shell if you can, which will make you swim faster, and watch out for the obstacles by every ring. Once through all rings, a Power Star will appear. Swim past a very unhappy Guppy, and claim your well deserved Power Star.

Star 4 (Daredevil Comet): Ghost Ship Daredevil Run
This Star is the boss fight from Star 1, with just one life point.

Star 5 (Purple Comet): Plunder the Purple Coins
100, no time limit. In ghost ship area. Some in water behind you at start. Some you'll need to crouch jump for - look for shadows. Need to jump out of water for some.

Star 6 (Hidden): Boo in a Box
Enter Star 1. Use shell underwater to destroy mines.