While on the dawn treader they discover The Dark Island. You cannot see anything, for everything is pitch black and all your dreams come true, even your worst nightmares! The solution is for Aslan to come save you.
Dragon Island
In Lone Island they all got seperated from each other. They got kidnapped. The kidnappers sold each of them as slaves.
Ramandu's Island
They discovered Death Water also on the Dawn Treader. As you can see from the name, this island is deadly. Water can turn anything into gold, including people! Just a drop of water can turn anything or anyone into gold!
The Island of Voices
The next island is Dragon Island. In this island Eustace tries to steal gold and turns into a dragon. The solution is for Aslan to peel the dragon skin off.
On the dawn treader they also find Ramandu's Island. In Ramandu's Island you have to go and wake up the three lords. In order to that you have to get to the end of the world and leave someone behind
Again in the Dawn Treader they discovered The Island of The Voices. In the Island of the voices were invisible people. You could hear them speak but since they were invisible, you couldn't see them.