Great way to see the River on your own schedule however closest stop to St Paul's is the Tower of London . That is s bit of a hike for older adults or a cab ride to get to the Cathedral.There are only 4 stops on the cruise but you can ride the boat all day or hop on /off. We have fabulous pictures from the boat including unbelievable sunset pictures . The only downside is if you want to spend time in Greenwich, you might need to run through St Paul's or forego it . We did take the boat out to Greenwich but as the return trip to London is between 5 and 6 pm we did not get to see the town . I would do the cruise again with this company as they have an open top deck and not all of the cruise companies do, just do St Paul's on a separate day if you want to see Greenwich.
Really loved this tour, and I recommend to take the long version of it once you reach. You will have the option to take a short and longer tour. It's a place filled with history and you would want to know as many stories as you can. It makes the tour more interesting and enjoyable.
It's good and worth the visit.
Long walk from the pier to the Cathedral, looked shorter on the map
Very exciting especially with sunny weather !