These cruise boats leave Westminster Pier for Greenwich, stopping at the Tower of London. Every second service continues on from Greenwich to the Thames Barrier (one way adult/child £10.40/5.20, return £12.80/6.40, hourly 11.30am to 3.30pm) but does not land there, passing the O2 along the way. From Westminster it’s a two-hour round trip to Greenwich, three hours to the Thames Barrier; from Greenwich the round trip to the barrier takes one hour. From November to March there’s a reduced service from Westminster to Greenwich, with eight daily departures between 10.40am and 3.20pm.