Check out this guide on The Floating Fortress (Buoy Base galaxy) Hidden Star in Super Mario Galaxy Switch (All Stars 3D). Includes how to unlock the Hidden Star, how to get, and location!
The Secret Of Buoy Base - How To Unlock
Swim Close To Bottom Of The Area
Jump to the water and swim down close to the bottom. You will find a caged green pipe there.
Lure One Of The Missiles To The Green Pipe
The only way to get to the green pipe is to lure one of the underwater missiles towards it. Just make sure not to get hit by it since it takes one life per hit.
Enter The Green Pipe
After the cage is broken, simply enter the green pipe.
The Secret Of Buoy Base - How To Get Hidden Star
The Secret Of Buoy Base Walkthrough Procedure Chart
|1||Lure one of the Bills to the cage in the middle of the platform encasing the Green Star|
|2||Grab the Green Star|
1. ~ 2. Grab The Green Star - Tips
3 Missiles Will Chase You At A Time
There will always be 3 missiles at a time that will chase after you in this section of the mission. You can have them collide with each other to destroy them.