Miyajima is an island located about 45 minutes away Hiroshima and is easy to get to by the local train. From the train stop, there is a ferry across the street that runs about every 20 minutes to take people to the island. There are several things to see at Miyajima, including the Itsukushima Shrine, famous for its tori gate placed out in the water. The shrine itself is like a series of docks and painted bright orange.
There are several hiking trails on the island, several of which lead to Mt. Misen, the highest point in elevation on Miyajima. One way to reach the top without hiking all day is by taking the cable cars to a lookout point. From this point you can hike for about an hour, enjoying small temples and man-made shrines, before reaching the summit. On a clear day you can see all the surrounding islands, while I was there it started to snow so I couldn’t really see much but it was still worth the hike.