Rapid Ride

Iza's River Rapid Ride, or just Rapid Ride, is an event that takes place in Twilight Princess, and is located in Upper Zora's River, in Lanayru Province. It is run by Iza and her Zora friend. To get to it, you must have access to Zora's Domain.

If you speak to Iza, she will simply ignore you. Walk around the area beside the fishing hole as human Link and soon you'll be attacked by Shadow Beasts. Defeat them, and Iza will let you in to her hut. She will request you help her out by clearing a path downstream. If you agree to clear the debris that have clogged the flow of the river, she will lend you a bomb bag, and fill up your quiver with arrows. Shoot the rocks visible from the hut's interior with bomb arrows twice, and you can get into a canoe. About halfway down the River, Iza's Zora will appear, and ask you to blow up a rock. Do it, and Iza's Zora will guide you the rest of the way(she will leave a trail of water ripples and Rupees). Get to Lake Hylia, and the Zora will let you keep the Bomb Bag Iza lent you.

Later in the game, return to Iza's hut. This time, you have to smash pots that you see using bomb arrows (yellow ones are worth 1 point, red ones 2 points). Score at least 25 points by the time you reach the Lake, and the Zora will double your bomb capacity in all bags that you currently have, and all bags that are received in the future.

Trivia
Inside Iza's Hut, there is a yellow pot which can be destroyed with bomb arrows. Destroy it, and Iza says to stop destroying her stock. Do this again, and you have to pay 10 Rupees.

A similar setting of riding in a boat down Waterfall Rapids will appear in the game, Link's Crossbow Training.