Mario and luigi bowsers insie story help?

I cant seem to get past this part of the game where bowser is drinking the water and mario and luigi are swimming around. ive gotten every puzzle piece and battled all the opponents. imjust stuck. what should i do/go?Mario and luigi bowsers insie story help?
Well, you should have gotten fire flower and green shell as for your puzzle pieces. Other than that, the path to the boss is pretty straightfoward. If you can't find a path, try swimming around.



I forgot, but if you're at the part when you hit a switch and a red ball-like thing comes out, that part is simple. Fill Bowser with water and the ball will float up. You should see jellyfish-like things at the left and right parts of the screen. Push the ball either left or right and let the jellyfish suck it up.



If you're stuck on the cannon part (where you have to shoot the ball), simply push the ball to the cannon and to the next area, then drop it in the cannon and hit the switch to activate the cannon.



Otherwise, use youtube.