To venture deep into the cave of Volcano Planet in Saihao, and face off against the Fire Deer Rio, you need to wear a spray suit and pave the way to proceed.
Saihao Spray Suit Acquisition Method: (If you already have it, please ignore this, and thank you for your attention.)
It's very simple. Go to the machine room, click on the water gun training in the lower left corner, and play a small game.