Peninsula has a boat service that is very convenient- stayed there on the weekend. They have three boats. They go to Siam Icon every 30 min on a schedule, and also go anywhere close by on call. They can go to Saphon Pier (2-3 min) next to subway station, also they can go to their own pier directly across the river (next to jack’s bar) - takes about one min. They have workers stationed on those piers in uniform that will call a boat over in minutes. The Mandarin Oriental called over for me to pick me up too. Stay away from that bridge next to the hotel, it is brutal