Runs a photogenic one-hour cruise taking in the National Theatre, Štrelecký island and Vyšehrad, departing at 11am, 2pm, 4pm, 5pm and 6pm April to September (adult/child 260/160Kč). Also offers a 1¼-hour boat trip to Troja (near the zoo; 190/140Kč one-way, 290/180Kč return) departing four times daily from May to August, and three times daily at weekends in April and September.
See the website for several other more ambitious day cruises. The boats depart from either Rašínovo nábřeží or Čechův Most in the Old Town. Consult the online schedule to check where the boats leave.