Wat Yan Nawa, the Boat Temple, is one of Bangkok's more unusual temples. King Rama III rebuilt the old Ayutthaya-period wat in the early nineteenth century and added a Chinese junk-shaped structure, preserving the memory of the sailing ships that once dominated trade on the Chao Phraya.
It is a good stop if you are near Sathorn Pier and want a temple that feels different from the royal set pieces around Rattanakosin.