It may surprise you to learn that The Voyage of the Dawn Treader draws not only on Christian theology but also on Celtic, especially Irish, mythology. As a professor of languages and literature, C.S. Lewis was well-versed in early British myths and legends, and both the voyage across the sea and the importance of sunrise have Celtic associations.
In The Voyage of the Dawn Treader, Caspian and his friends sail through the Eastern seas, braving storms and monsters as they visit a series of magical islands, eventually arriving at Aslan's country, a place "outside the world" (16.53) that seems a bit like heaven and a bit like fairyland. Similarly, there are many ancient Irish myths in which great heroes (and sometimes ordinary guys) sail across the seas, endure raging storms, visit strange islands, and in the end make it to the Otherworld, a creepy and intimidating fairy land where you definitely do not want to get stuck.
If you start reading some of these legends, you might be shocked at how many plot elements they share with The Voyage of the Dawn Treader. One good example is the story of Mael Duin, the oldest known Celtic travel myth. Mael Duin is a hero who swears to avenge his father's death and sets out on a sea voyage to find the killers – just like Caspian, who swears to find his father's exiled allies. When Mael Duin sets sail, his three foster brothers jump into the sea and he has to take them on board the ship and let them join him so they won't drown – which sounds a lot like the way that Edmund, Lucy, and Eustace arrive on the Dawn Treader. Mael Duin also visits a lot of strange magical islands (although the details are different from the islands in the seas of Narnia). At the end of his voyage, Mael Duin, like Caspian, marries a mystical queen whom he meets on the last island he visits. Other elements that the two stories share include a rebellion of the crew, being guided by magical birds, and finding an intimidating fantasy world at the end of the voyage. If you're interested in C.S. Lewis's use of Irish mythology, we suggest you head to your favorite bookstore or library and pick up a book of Celtic legends.
Oh, and just to make it clear: The Voyage of the Dawn Treader definitely alludes to other, non-Celtic myths and legends about great voyages, too. The most obvious is Homer's Odyssey. So don't go away thinking that this book is just Christian symbols meet Celtic ones – there's also some Greek mythology in the mix, plus a lot of other things. We're just taking some time to explain the Celtic allusions because they might be unfamiliar to you.
As we've mentioned in the "What's Up With the Title?" section, The Voyage of the Dawn Treader has a lot to do, symbolically speaking, with the dawn. Caspian's voyage is specifically a journey to the extreme eastern end of the world – which, in the flat world of Narnia, not only means in the direction of the sunrise, but also actually getting closer to the sun. Many different ancient cultures worshipped the sun and considered events like the sunrise to be sacred, but the Celts took this to an extreme. Many of their holidays were related to solar events like eclipses, solstices, and equinoxes; they had several gods of the sun; and they put a lot of effort into tracking the sun's position in the sky. The scene at the beginning of Chapter 14, in which Ramandu and his daughter face the sunrise and sing while surrounded by stone pillars and an enormous feast, is extremely reminiscent of a Celtic festival. Just imagine druids in the middle of Stonehenge with an offering of harvest fruits, worshipping the sun as it comes up, and you can see the allusion.