Hornblower is the newer boat company in town, taking over from the age-old Maid of the Mist (which still runs on the American side of the falls). Hornblower's 700-person catamarans sail up close to Bridal Veil Falls and Horseshoe Falls, among other thundering cascades. You are supplied flimsy raincoats but will still get doused (in a fun way).
Departures are every 15 minutes, weather permitting. Sunrise and evening fireworks cruises are being added to the schedule, so check for updates.