We recently took a double kayak out into Hanalei Bay for the afternoon and sunset. You can rent kayaks at the end of Wiki Rd or in town at one of the rental places on the edge of town. They give you everything you need but you may want to have a waterproof bag for your car keys and wallet, they can be attached to the kayak so you won’t loose them! Make sure to plan your paddle on a day when the Bay is calm and the surf is low.
You can put in at the mouth of the Hanalei River and paddle up the river and see the taro fields of the valley or you can go the other way and paddle into the Bay. If you paddle to the right you will go in front of the St Regis Princeville where there is a reef and some great snorkeling. You can in calm surf continue around the point (ocean-side) and reach Hideaways Beach which also has fantastic snorkeling! Be sure to watch the ocean conditions!
Paddling to the left into Hanalei Bay you can enjoy some great views, clear waters and lazy afternoons! Summer time (Mid Alril-September) you will have many other boats in the water along with paddle boarders, surfers and kayakers; in the winter the moored boats are gone, surf can be rough and it is recommended to paddle only on calm days. Hanalei Bay does have 2 lifeguard stations which are spaced out on the Bay.
It doesn’t get any better than this on a calm day! If you are comfortable in the water and want to try kayaking this is the place to do it!