It does this to let the big ships through to the Pool of Lon

这样做的目的,是让大型船只得以通过,从而驶往“伦敦池”.
提醒：The Pool of London is a part of the Tideway of the River Thames from London Bridge to below Tower Bridge.It was the original part of the Port of London.伦敦池是泰晤士河感潮段的一部分,位于伦敦桥和塔桥之间,构成最初的伦敦港.