Whether you are a local or a tourist looking to access the island, I highly recommend the water taxi service. It moves way more quickly than the ferries, its way more fun, and certainly more comfortable.
The pricing is fair considering your are getting a VIP ride, and remember city permits and gasoline done not come cheap.
TIP: be sure to confirm your destination points and times before departure with the Captain. They are regulated by the city on where they can operate and stop.
If you really enjoy the ride and your entertaining Captain, consider leaving a cash tip.
Amazing customer service.
Now get out there, and enjoy the lake and island!