The harbor channel and Bahía de la Habana (Havana Bay) separate Habana Vieja [1] from the communities of Casablanca, Regla [2], and Guanabacoa [3]. The latter districts draw tourists interested in santería and Afro-Cuban music and dance, while Casablanca is an access point to the Parque Histórico Militar Morro-Cabaña [4].
Little ferries bob their way across the harbor, connecting Casablanca and Regla with each other and with Habana Vieja.
Links:
[1] http://www.moon.com/destinations/cuba/havana/sights-habana-vieja
[2] http://www.moon.com/destinations/cuba/havana/sights-across-the-harbor/regla
[3] http://www.moon.com/destinations/cuba/havana/sights-across-the-harbor/guanabacoa
[4] http://www.moon.com/destinations/cuba/havana/sights-across-the-harbor/parque-historico-militar-morro-cabana