Venice--Aqua alta

Acqua alta (pronounced [ˈakkwa ˈalta] ( listen); Italian for "high water") is the term used in Veneto for the exceptional tide peaks that occur periodically in the northern Adriatic Sea. The peaks reach their maximum in the Venetian Lagoon, where they cause partial flooding of Venice and Chioggia;

http://archive.boston.com/bigpicture/2008/12/venice_under_water.html

https://www.theguardian.com/cities/gallery/2015/jun/16/history-flooding-sinking-city-venice-in-pictures

Venice: tourists on the gangways queuing to enter the San Marco basilica.

http://www.italyheaven.co.uk/veneto/venice/acqua-alta-photos1.html

During acqua alta, the passarelle (walkways) are put up very quickly

http://www.travelsignposts.com/destination/Italy/Venice/Venice-Aqua-Alta/venice-acqua-alta_AJP0653