Question: Between Haikou and Gaizhou, which city is located further south of China?

Context articles: Haikou
Gaizhou
Haikou Meilan International Airport
Shapo Reservoir
Movie Town Haikou
Century Park (Haikou)
Evergreen Park (Haikou)
South Port
Hainan Western Ring Railway
Bo'ai Road area

Hǎikǒu (), is the capital and most populous city of Hainan province, China.
 It is situated on the northern coast of Hainan, by the mouth of the Nandu River.
 The northern part of the city is the district of Haidian Island, which is separated from the main part of Haikou by the Haidian River, a branch of the Nandu.
Gaizhou (), formerly Gaixian and Gaiping, is a county-level city in Liaoning province, southwest China.
 It is under the administration of Yingkou City, which lies 31 km to the north-northwest, and is located at the northwest end of the Liaodong Peninsula near the northeast coast of the Bohai Sea.
Haikou Meilan International Airport (IATA: HAK) is the airport serving Haikou, the capital of Hainan Province, China.
 It is located 25 km southeast of the city center and was opened in 1999, replacing the old Dayingshan Airport located along what is now the city's Guoxing Avenue (国兴大道).
 The airport is operated by HNA Infrastructure.
The Shapo Reservoir (shaposhuiku) is located 5 km south of Haikou city, Hainan, China, south of Shapo Village at Chengxi Town.
 The purpose of this reservoir is to prevent floods and conserve water for supply to Haikou.
 It is roughly 2 km long.
 A single dam is located at the east side with an adjacent water outlet.
 Water released from this dam flows into a spillway and then starts the Meishi River.
 This narrow river then flows eastward under Longkun Road just south of the Haikou East Railway Station.
 It then turns north and empties into the Haidian River.
Movie Town Haikou (海口电影公社) is an artificial town, movie studios, guest apartments, and administration buildings, approximately 8 km south of Haikou, Hainan, China.
 The town, located beside Mission Hills Haikou golf resort, was created as a movie and television filming location and tourist attraction.
 Some of the buildings still under construction are the town buildings and the movie studios with accompanying filming facilities.
Century Park (世纪公园) is an 8.40-hectare, public park located downtown Haikou, in the Longhua district of the city, Hainan Province, China.
 It is located northwest of Binhai Park and east of Evergreen Park.
 The Haikou Century Bridge travels over part of it.
Evergreen Park (万绿园) is a public park located in Longhua District, Haikou, Hainan Province, China.
 It is the largest park in the city, and is situated between Bin Hai Road and the north coast of the main part of Haikou.
 The park contains approximately ten thousand coconut trees and hundreds of species of South Asian ornamental plants.
 It was opened in January 3, 1996, and is the main site of many of the city's festivals and events.
 It contains an artificial lake, a small amusement park, and various kiosks.
South Port is a port located on the western coast of Xiuying District, Haikou, Hainan, China.
 It operates as the south terminal of the Yuehai Ferry service, part of the Guangdong–Hainan Railway.
 This ferry transports train cars across the Qiongzhou Strait between the Leizhou Peninsula at the southern tip of Guangdong on mainland China, and the northern coast of Hainan.
 Ferry boats arrive at South Port, unload the train cars onto tracks.
 The train cars then proceed a few hundred metres southeast to the Haikou Railway Station which is the last stop on the Guangdong–Hainan Railway.
The Hainan Western Ring Railway () is a standard-gauge railway running along the coast of the western half of Hainan Island in South China.
 It connects the provincial capital Haikou on the island's north coast with Sanya, the major city on Hainan's south coast.
 The rail line is 363.8 km long; its terminals are Haikou Railway Station and Sanya Railway Station.
 Cargo trains enter this railway from Zhanjiang, Guangdong at the South Port of the Guangdong–Hainan Railway.
The Bo'ai Road area () is a historical neighbourhood in Haikou City, Hainan, China.
 It is located on the south side of the Haidian River, at the northern part of mainland Haikou.
 The main hub of the neighbourhood is the north-south Bo'ai Road itself, a commercial road with shops selling such items as fabrics, wholesale toys, and pets, in particular freshwater fish.