It rises from the sea floor to a depth of 593 m (1,946 ft) and is located between Taʻu and Rose islands at the eastern end of the Samoa hotspot chain.

Two principal rift zones extend east and west from the summit, parallel to the trend of the Samoan hotspot.

[9] Vailuluʻu is a conical seamount[10] and reaches a depth of 593 metres (1,946 ft) and features a 2 kilometres (1.2 mi) wide and 0.4 kilometres (0.25 mi) deep crater;[1] the shallowest part of the seamount is located on the western crater rim[11] which has a scalloped appearance.

[21] Vailuluʻu lies at the eastern end of the Samoan volcanic chain[1] and is considered to be the present-day location of the Samoa hotspot;[7] this interpretation is based on both the position of the seamount and the isotope ratios of rocks taken from it.

[3] Young rock ages have also been observed on Malumalu Seamount,[22] implying that the hotspot is currently feeding both volcanoes[23] and forming two separate volcanic chains.

[27] The Malulu Seamount and Rose Island east of Vailuluʻu do not appear related to the Samoa hotspot system,.

[26] This hotspot is under the influence of the mantle flows triggered by the Tonga Trench, which distort the rising plume[23] and also changes its upwelling flux.

[32] Iron oxide chimneys with sizes measured in centimetres to metres[19] have been formed by low temperature hydrothermal venting.

[34] A number of mostly pigmented yeasts and other fungi have been identified in deposits from the Nafanua Cone and in iron mats[35] and might play important roles in the ecosystems of Vailuluʻu.

[36] Microbial mats[37] with thicknesses of 2–4 centimetres (0.79–1.57 in) (though possibly thicker in depressions) have been found at Vailuluʻu;[7] they often contain iron hydroxide/iron oxide deposits.

[40] Demosponges have been observed in breaches of the crater rim and presumably rely on incoming nutrient-rich water from the ocean, while crinoids,[40] gorgonians, ophiuroids and sponges have been found on the western rift zone of Vailuluʻu.

For example, the oxygenated waters and availability of shrimp as food source attract eels to the summit of Nafanua, while the crater floor[1] displays a high animal mortality and is called the "moat of death";[11] polychaetes feeding on dead fish have been found on the crater floor.

[40] This is due to the very low availability of oxygen for respiration at the crater floor, unlike at the summit of Nafanua cone.

[50] Dredge samples showed fresh rocks; radiometric dating produced ages of less than ten years according to 1984 and 1999 publications.

[46] The last eruption, between 2001 and 2004, went unobserved[24] and formed the Nafanua volcanic cone;[48] for the most part, the shape of the volcano has not changed over time.