I think a good classic would be "Treasure Island" then, pirates, ships, hidden treasures and betrayals all around. "Gulliver's Travels" is a good one as well, very fictional though.

And... If you feel adventurous and want to give a try to books that are a bit different from what you asked, any novel by Natsume Soseki would be good. I've seen two of his works, Kokoro and Sanshiro at the library. Don't expect fighting in those thought, the exploration they do is more... Spiritual than physical. But they are still good.