To 17 ports; the busiest crossings are to Tower of London (26 minutes, 47 times a day), Greenwich (52 minutes, 47 times a day), Embankment (4 minutes, 37 times a day), Bankside (16 minutes, 37 times a day), London Bridge (22 minutes, 37 times a day), Canary Wharf (38 minutes, 37 times a day), North Greenwich (an hour, 37 times a day) and Surrey Quays (42 minutes, 35 times a day).