In Chidorigafuchi, you can enjoy a boat ride in cherry blossom (Sakura) season (For access and general information on Chidorigafuchi, see Chidorigafuchi: Cherry Blossom). The Boat dock is located in middle of the park road. Business hours are from 9:00 AM. to 8:30 PM. Fare is 800 yen per 30 minutes. See Official Site for detailed information.
You can enjoy very distinct views by looking up Sakura from water level. However, as it is very crowded, please remember visiting with extra time.