When you take a standard trip on its generously glass-sided and -topped boats, live narrators point out details of interest. The “Red Rover” ticket allows you to hop on and off all day. Boats go every 30 minutes, generally between 9am and 9pm, at four piers: Westminster, London Eye, the Tower, and Greenwich. Note that two of those stops are across the river from each other, leaving the stretch between the London Eye and the Tower of London (the meatiest section) without a stop. Using it to add Greenwich can save money off buying several one-way tickets on standard ferries, but simple return tickets are cheaper on Thames Clippers. The 40-minute London Eye River Cruise (londoneye.com; [tel] 0870/500-0600; £12 adults, £6 children 5–16; daily 11:45am–4:45pm), from London Eye pier, is less of a value because you can’t get off to explore.