Here is the info from the Disney website regarding the jet ski tour at
castaway cay.
Personal Watercraft Eco Tour (1 hour)
Get to know Castaway Cay like a native! A knowledgeable guide will take you on a fascinating 1-hour eco adventure via personal watercraft as you learn about the area's abundant marine life, unique ecology and storied history. First, your guide will lead the way to a scenic stop amid the mangroves, where you'll learn about Castaway Cay's intriguing ecosystem. Then, it's off to a second point of interest, where your guide will describe the colorful history of The Bahamas and the unique island marine life. You may ride either singly or in pairs on this exciting journey-why not make it a family affair? The entire adventure, including PWC instructions will last approximately 1 hours. It is recommended to wear water shoes or sandals, as well as eyeglass straps. To ride, you must be at least 8 years old. To drive, you must be at least 18 years old. Guests ages 16 or 17 years old who wish to drive may do so with written authorization from a parent or guardian. Riders will board watercraft from the water.
Adult Price: $160 for a double; $95 for a single rider (ages 8 and above)
Child Price: $N/A
Departure Time: 9:45, 10:30, 11:15 am, 12:00, 1:00, 1:45, and 2:45 pm