The London Pass is a card that allows you free access to the main tourist attractions it offers London. Their prices vary depending on whether you want a 1-day, 2-day, 3-day pass, etc. Among the attractions included are boat trips on the Thames. You can access their website by clicking this link. You have all the information in: «How much money to bring to London according to the duration of the trip«.
You have all the information in: "How much money to bring to London according to the duration of the trip".