Gunkanjima
Proper noun
ぐんかんじま
アイツはぜんぜん面白くないな。話題といったら軍艦島の都市伝説だけだし。
He isn’t interesting at all. All he talks about is the urban legend of Battleship Island.
A 軍艦 is a battleship, and 島 is an island. Welcome to... Battleship Island (go Jurassic Park music).
This word uses the on'yomi readings for 軍 and 艦, and the kun'yomi reading for 島. You learned all of them, so you should know the reading already! Oh, but watch out for the rendaku.