Hey fellow Final Fantasy X explorer! When it comes to side quests, there are a few key ones you definitely don’t want to miss out on.

1. **Monster Arena:** By capturing and battling monsters, you can earn some amazing rewards and even unlock some powerful abilities for your characters. It’s a great way to level up and customize your party.

2. **Celestial Weapons:** Each character has a unique Celestial Weapon that can be obtained by completing challenging tasks. These weapons are incredibly powerful and are essential for taking on some of the toughest bosses in the game.

3. **Dark Aeons and Penance:** Once you’ve powered up your party, you can take on the Dark Aeons and the super boss, Penance. These battles are some of the toughest in the game, but the rewards are definitely worth it if you can emerge victorious.

Make sure to explore every nook and cranny of Spira to uncover all the hidden treasures and secrets the game has to offer