Miyajima island has more to offer then it's great touristic places, if you have already seen Itsukushima Shrine, the famous red floating shrine or the Buddhist Daisho-in Temple and perhaps you have also climbed Mt. Misen and enjoyed the views. However, there is still a lot more to see on this island. Taking a walk through the small streets in the charming old town is kind of peaceful and refreshing. There are lots of traditional Japanese houses, small temples and interesting shops.
Follow the tunnels and roads that go past the aquarium to find a road along the shore that leads to many different, but very nice, beaches on the left and an untamed forest on the right. From time to time there are paths leading into the forest, probably used by the deer.
I think in summer it must be great to go swimming at the beaches :)