Miyajima can be reached by sea from Hiroshima. The main ferry terminal on the mainland is Miyajimaguchi, which can be reached from JR Hiroshima station either by train (�400, 25 minutes, or �570 for a combination ticket with the ferry) or tram line #2 (�270, 70 minutes). The tram line also passes by the Peace Memorial Park.
From Miyajimaguchi, JR ferries and Matsudai ferries run to Miyajima up to 10 times per hour. The trip takes 10 minutes and costs �170 each way; Japan Rail Pass holders can use the JR ferry for free. The last ferry returns to the mainland at 10:40PM. Most tour groups are gone after 5PM, so you'll have a different experience on the island if you wait them out.
There are also direct ferry connections from the Motoyasubashi Pier of the Hiroshima Peace Park, run by Aqua Net, with departures once per hour between 8:50AM and 6:50PM (returns between 9AM and 5:05PM). It's a scenic 50 minute ride, but these charge a steep �1900 one-way, �1500 return (half-price for children). Direct connections are also available from Ujina Port in Hiroshima, allowing connections with Matsuyama.
There is another ferry which can be caught from Hiroshima port, stopping at the Rprince Hotel. It is more expensive than the other ferries, costing �3100 for a return journey, but it does take a slightly more scenic route.
No bridges connect Miyajima to the mainland. Some ferries will carry automobiles and motorcycles, but parking on the island is expensive and difficult to find, unless arranged in advance with a hotel on the island, and most of the sights can't be reached by car. Quite a few of the hotels are willing to pick guests up from the pier with advance notice, though
