Upolu is an island in Samoa, formed by a massive basaltic shield volcano which rises from the seafloor of the western Pacific Ocean. The island is 75 kilometres long and 1,125 square kilometres in area, making it the second largest of the Samoan Islands by area. With approximately 145,000 inhabitants, it is by far the most populous of the Samoan Islands. Upolu is situated to the southeast of Savai'i, the "big island". Apia, the capital, is in the middle of the north coast, and Faleolo International Airport at the western end of the island. The island has not had any historically recorded eruptions, although there is evidence of three lava flows, dating back only to between a few hundred and a few thousand years ago.

Samoa, officially the Independent State of Samoa and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ; two smaller, inhabited islands ; and several smaller, uninhabited islands, including the Aleipata Islands. Samoa is located 64 km (40 mi) west of American Samoa, 889 km (552 mi) northeast of Tonga, 1,152 km (716 mi) northeast of Fiji, 483 km (300 mi) east of Wallis and Futuna, 1,151 km (715 mi) southeast of Tuvalu, 519 km (322 mi) south of Tokelau, 4,190 km (2,600 mi) southwest of Hawaii, and 610 km (380 mi) northwest of Niue. The capital and largest city is Apia. The Lapita people discovered and settled the Samoan Islands around 3,500 years ago. They developed a Samoan language and Samoan cultural identity.