Reference article
Archery Cave
An archery challenge where shooting targets opens the route to Crystal Key A.
Guide
Move and aim, then use the shoot control to hit the targets in each section. Clear the targets to open the next gate. Finish before the time bar empties; failed attempts give you more time on the next try.
Reward
Collect Crystal Key A at the end. It is one of the three 
Crystal Keys needed to open the gate to the tournament grounds.