Question: What was the 2018 population of the Italian city that's underwater?

Knowledge 1: Venice
Venice (/ ˈvɛnɪs /, VEN - iss; Italian: Venezia (veˈnɛttsja) (listen); Venetian: Venesia, Venexia (veˈnɛsja)) is a city in northeastern Italy and the capital of the Veneto region. It is situated across a group of 118 small islands that are separated by canals and linked by 400 bridges. The islands are located in the shallow Venetian Lagoon, an enclosed bay that lies between the mouths of the Po and the Piave rivers (more exactly between the Brenta and the Sile). Parts of Venice are renowned for the beauty of their settings, their architecture, and artwork. The lagoon and a part of the city are listed as a UNESCO World Heritage Site. [SEP] Knowledge 2: Venice
Venice Italian: Venezia Comune Comune di Venezia A collage of Venice: at the top left is the Piazza San Marco, followed by a view of the city, then the Grand Canal, and (smaller) the interior of La Fenice and, finally, the Island of San Giorgio Maggiore. Flag Venice Location of Venice in Veneto Venice Venice (Italy) Venice Venice (Europe) Show map of Veneto Show map of Italy Show map of Europe Show all Coordinates: 45 ° 26 ′ 15 ''N 12 ° 20 ′ 9'' E ﻿ / ﻿ 45.43750 ° N 12.33583 ° E ﻿ / 45.43750; 12.33583 Coordinates: 45 ° 26 ′ 15 ''N 12 ° 20 ′ 9'' E ﻿ / ﻿ 45.43750 ° N 12.33583 ° E ﻿ / 45.43750; 12.33583 Country Italy Region Veneto Metropolitan city Venice (VE) Frazioni Chirignago, Favaro Veneto, Mestre, Marghera, Murano, Burano, Giudecca, Lido, Zelarino Government Mayor Luigi Brugnaro (independent) Area Total 414.57 km (160.07 sq mi) Elevation 1 m (3 ft) Population (2018) Total 260,897 Density 630 / km (1,600 / sq mi) Demonym (s) (it) Veneziano, pl. Veneziani (en) Venetian, pl. Venetians Time zone UTC + 1 (CET) Summer (DST) UTC + 2 (CEST) Postal code 30100 Dialing code 041 ISTAT code 027042 Patron saint St. Mark the Evangelist Saint day 25 April Website Official website
Knowledge 1: Venice
Venice Italian: Venezia Comune Comune di Venezia A collage of Venice: at the top left is the Piazza San Marco, followed by a view of the city, then the Grand Canal, and (smaller) the interior of La Fenice and, finally, the Island of San Giorgio Maggiore. Flag Venice Location of Venice in Veneto Venice Venice (Italy) Venice Venice (Europe) Show map of Veneto Show map of Italy Show map of Europe Show all Coordinates: 45 ° 26 ′ 15 ''N 12 ° 20 ′ 9'' E ﻿ / ﻿ 45.43750 ° N 12.33583 ° E ﻿ / 45.43750; 12.33583 Coordinates: 45 ° 26 ′ 15 ''N 12 ° 20 ′ 9'' E ﻿ / ﻿ 45.43750 ° N 12.33583 ° E ﻿ / 45.43750; 12.33583 Country Italy Region Veneto Metropolitan city Venice (VE) Frazioni Chirignago, Favaro Veneto, Mestre, Marghera, Murano, Burano, Giudecca, Lido, Zelarino Government Mayor Luigi Brugnaro (independent) Area Total 414.57 km (160.07 sq mi) Elevation 1 m (3 ft) Population (2018) Total 260,897 Density 630 / km (1,600 / sq mi) Demonym (s) (it) Veneziano, pl. Veneziani (en) Venetian, pl. Venetians Time zone UTC + 1 (CET) Summer (DST) UTC + 2 (CEST) Postal code 30100 Dialing code 041 ISTAT code 027042 Patron saint St. Mark the Evangelist Saint day 25 April Website Official website [SEP] Knowledge 2: Philadelphia
Historically, Philadelphia sourced its water by the Fairmount Water Works, the nation's first major urban water supply system. In 1909, Water Works was decommissioned as the city transitioned to modern sand filtration methods. Today, the Philadelphia Water Department (PWD) provides drinking water, wastewater collection, and stormwater services for Philadelphia, as well as surrounding counties. PWD draws about 57 percent of its drinking water from the Delaware River and the balance from the Schuylkill River. The public wastewater system consists of three water pollution control plants, 21 pumping stations, and about 3,657 miles of sewers. A 2007 investigation by the Environmental Protection Agency found elevated levels of Iodine-131 in the city's potable water.[citation needed] In 2012, the EPA's readings discovered that the city had the highest readings of I-131 in the nation. The city campaigned against an Associated Press report that the high levels of I-131 were the results of local gas drilling in the Upper Delaware River.[citation needed]
Knowledge 1: Venice
Venice Italian: Venezia Comune Comune di Venezia A collage of Venice: at the top left is the Piazza San Marco, followed by a view of the city, then the Grand Canal, and (smaller) the interior of La Fenice and, finally, the Island of San Giorgio Maggiore. Flag Venice Location of Venice in Veneto Venice Venice (Italy) Venice Venice (Europe) Show map of Veneto Show map of Italy Show map of Europe Show all Coordinates: 45 ° 26 ′ 15 ''N 12 ° 20 ′ 9'' E ﻿ / ﻿ 45.43750 ° N 12.33583 ° E ﻿ / 45.43750; 12.33583 Coordinates: 45 ° 26 ′ 15 ''N 12 ° 20 ′ 9'' E ﻿ / ﻿ 45.43750 ° N 12.33583 ° E ﻿ / 45.43750; 12.33583 Country Italy Region Veneto Metropolitan city Venice (VE) Frazioni Chirignago, Favaro Veneto, Mestre, Marghera, Murano, Burano, Giudecca, Lido, Zelarino Government Mayor Luigi Brugnaro (independent) Area Total 414.57 km (160.07 sq mi) Elevation 1 m (3 ft) Population (2018) Total 260,897 Density 630 / km (1,600 / sq mi) Demonym (s) (it) Veneziano, pl. Veneziani (en) Venetian, pl. Venetians Time zone UTC + 1 (CET) Summer (DST) UTC + 2 (CEST) Postal code 30100 Dialing code 041 ISTAT code 027042 Patron saint St. Mark the Evangelist Saint day 25 April Website Official website [SEP] Knowledge 2: Mexico City
The city grew as the population did, coming up against the lake's waters. As the depth of the lake water fluctuated, Mexico City was subject to periodic flooding. A major labor draft, the desagüe, compelled thousands of Indians over the colonial period to work on infrastructure to prevent flooding. Floods were not only an inconvenience but also a health hazard, since during flood periods human waste polluted the city's streets. By draining the area, the mosquito population dropped as did the frequency of the diseases they spread. However, draining the wetlands also changed the habitat for fish and birds and the areas accessible for Indian cultivation close to the capital.

Answer: 260,897