Enjoy a boat trip to the opposite side of the bay. I always buy a two-way ticket - it's a bit cheaper. The one-way journey takes about 15 minutes. On the other side, you can also take a walk around the local shops, go up on the lift, and then return by boat. Check the boat schedule here: Amanohashidate Sightseeing Boat.

Amanohashidate is the port you are departing from, and Ichinomiya is the port where you arrive on the opposite side of the bay.