Immerse yourself in the marine world by visiting the Saint-Malo Aquarium. Explore the diverse marine life, including sharks, turtles, and colorful fish. Learn about the local marine ecosystem and conservation efforts. Afterward, head to the Maritime Museum to discover the city's seafaring history. Admire the collection of model ships, navigational instruments, and artifacts. End the day with a leisurely stroll along the city walls, enjoying the panoramic views of the coastline.