What is the fine-grained topic of the following text: The mythical discoveries of Martin D'Augilar and Juan De Fuca are no longer shown, and the potential watercourse from the Bay of the West to the Michinipi River and then on the the Atlantic is now gone, although the names of the two explorers remain. Only return the topic.
Mythical discoveries of explorers Martin D'Augilar and Juan De Fuca