Discovery Centre is Halifax's hands-on science museum, set close to the waterfront and aimed squarely at curious children and adults who like to touch things rather than just read panels. Exhibits change, but the emphasis is usually on experimentation, technology, the body, oceans, and local science.
It is one of the better bad-weather options in the city, and a practical stop if you are travelling with kids who have had enough of ships, citadels, and boardwalk walking. Combine it with the waterfront museums and market rather than treating it as a full-day destination.