Cité de la Mer
Do this firstRight next to the cruise terminal — you can't miss it. The Cité de la Mer is a maritime museum built inside the old transatlantic liner terminal that once saw Titanic make its last port call before heading into the Atlantic. The building alone is extraordinary. Inside, the highlight is the Redoutable — a real 128-metre nuclear submarine that you can walk through. It takes about 90 minutes to do it justice and is genuinely one of the better museum experiences at any cruise port in Northern Europe.
