The Samoa hotspot is a volcanic hotspot located in the south Pacific Ocean. The hotspot model describes a hot upwelling plume of magma through the Earth's crust as an explanation of how volcanic islands are formed. The hotspot idea came from J. Tuzo Wilson in 1963 based on the Hawaiian Islands volcanic chain.

In theory, the Samoa hotspot is based on the Pacific Tectonic Plate travelling over a fixed hotspot located deep underneath the Samoan Islands. The Samoa hotspot includes the Samoan Islands (American Samoa and Samoa), and extends to the islands of Uvea or Wallis Island (Wallis and Futuna) and Niulakita (Tuvalu), as well as the submerged Pasco banks and Alexa Bank.

As the Pacific Plate moves slowly over the hotspot, thermal activity builds up and is released in magma plume spewing through the Earth's crust, forming each island in a chain. The Samoa islands generally lie in a straight line, east to west, in the same direction of the tectonic plate 'drifting' over the hotspot.

A characteristic of a “classic” hotspot, like the Hawaiʻi hotspot, results in islands located further from the hotspot being progressively older with newer and younger islands closest to the fixed hotspot, like the Kamaʻehuakanaloa Seamount (formerly Lōʻihi), the only submarine volcano in the hotspot chain which was initially studied in detail by scientists. The scientific research from Kamaʻehuakanaloa resulted in a 'Hawaiʻi' model for hotspots primarily limited to the information gathered from the Hawaiian Islands.

However, the Samoa hotspot has features that resulted in enigmas for scientists. In the Samoa Islands, the easternmost island of Taʻū and the westernmost island of Savaiʻi have both erupted in the past 150 years. The most recent eruption on Savaiʻi occurred with Mount Matavanu (1905–1911) and on Taʻū in 1866. This has been postulated to be due to enhanced rejuvenated volcanism associated with the close proximity to the northern Tonga Trench, which is just over 100 km (62 mi) south of the westernmost Samoan island of Savai’i. This volcanism was so voluminous that the entire island was covered with lava flows less than 1 million years of age. Compared to the previously most studied examples of late volcanism in the Hawaiian islands this was an excessive volume. Samples have been obtained showing that older Samoan hotspot composition lava of about 5 million years age underlaid this. It was further not understood initially that two members of the hotspot highway crossed just south of Samoa and that volcanoes in the Samoan region must be distinguished by age and/or geochemical composition to determine their hotspot of origin.

In 1975, geophysicist Rockne Johnson discovered the Vailuluʻu Seamount, 45 km east of Taʻū island in American Samoa which has since been studied by an international team of scientists and characterised as the youngest voclano of the Samonian hotspot chain. Within the summit crater of Vailuluʻu is an active underwater volcanic cone called Nafanua, named after a war goddess in Samoan mythology. The study of Vailuluʻu provides scientists with another possible model for hotspots as an alternative to the Hawaiʻi hotspot model.

An important difference between Vailuluʻu and Kamaʻehuakanaloa in Hawaiʻi, is a total lack of tholeiitic basalt compositions at Vailuluʻu although both are located at the easternmost point of their respective island chains.

The northern Tonga Islands (Vavaʻu and Niuatoputapu) are moving away from Fiji on the Australian Plate at rates of about 13 cm/year (5.1 in/year) and 16 cm/year (6.3 in/year), respectively, while Niue and Rarotonga on the Pacific plate are approaching the Australian plate at about 8 cm/year (3.1 in/year). This implies that Pacific plate is tearing at the corner of the trench-transform boundary at a rate that is the sum of these two (16 + 8) 24 cm/year (9.4 in/year).