Saint Joseph Cathedral is one of central Toamasina's clearest landmarks and the seat of the city's Catholic archdiocese. Its value for travellers is as much urban orientation as architecture: it gives a fixed point in a port city that can otherwise feel spread along roads, markets, and the waterfront.
Step inside if it is open, especially around service times when the building belongs fully to local life. It is a short visit, but a useful one for understanding Toamasina beyond the beach and port.