The wide island... this isn't helpful on its own, but this wide island is Hiroshima (heard of it?). When you do the reading it will make more sense.
The reading is the kun'yomi readings of both of these which is what you learned with the individual kanji. Just make sure you know those readings and you'll be able to read this.
Are there good mountains to climb in Hiroshima?
I'm heading into the city from Hiroshima airport by city bus.
The atomic bombs dropped on Hiroshima and Nagasaki instantly killed more than 100,000 people.