The CEDAM Shipwreck Museum — CEDAM stands for Club de Exploración y Deportes Acuáticos de México — occupies a small building near the marina and holds artefacts salvaged from Spanish colonial-era wrecks in the waters off the Yucatán Peninsula. The collection includes cannons, anchors, navigational instruments, ceramics, and personal items recovered from ships that came to grief along what was one of the most treacherous stretches of the old trade routes between the Americas and Spain.
It is low-key by any standard — no dramatic lighting, no multimedia — but the objects are genuine and the story of the colonial fleet is told with enough context to make it worthwhile. Entry is free or nominally priced, and it takes about half an hour to go through properly. Easy to combine with a walk along the marina.