Thames river cruise hop on hop offr r the thames river cruise hop on hop off sightseeing tour gives you the freedom enjoy all the famous sights of london from the ancient river thames and to hop on or off as many times as you like from any of the stops along the wayr r free child place with every adult ticket bookedr r get 1 free child place for every standard adult 1 day or 3 day ticket bookedr r please note for every 1 adult booked you will automatically receive a free child place included