Volcanic activity at Monowai Seamount was discovered between 1877 and 1924,[2] and a shoal was first noted in 1944 (although this may constitute a misinterpreted pumice raft or disturbance of the water.

[17] This activity is also responsible for frequent changes in its morphology[18] with up to 176 metres (577 ft) height variation recorded between surveys made in 1998, 2004 and 2007.

[16] Recent volcanic activity has smoothed the slopes of the Monowai Seamount[19] and covered them with lapilli sand and scoria in some places.

[25] On Mussel Ridge, a ridge located within the caldera and close to its southwestern margin,[22] seafloor observations have found cemented volcanic ash, dispersed rocks, mud,[27] pillow lavas, pillow tube lavas, and talus.

[30] In addition to "true" hydrothermal fluids, the slopes of Monowai are the sources of non-hydrothermal plumes that probably originate from landslides or when material is remobilized by eruptions.

[6] Behind the trench back-arc, spreading takes place at a rate of 15.9–1.5 centimetres per year (6.26–0.59 in/year) also with a southwards decreasing tendency.

The faults that dissect the Monowai Seamount have strikes and trends comparable to those of other volcanoes in the central Kermadec arc.

[5] Dredged samples contain phenocrysts of clinopyroxene, olivine, and plagioclase[36] and define a mainly mafic rock suite, which is unusual for a large caldera.

[38] On Mussel Ridge, hydrothermal alteration of rocks has produced several minerals like alunite, amorphous silica, anhydrite, barite, chalcopyrite, cristobalite, magnetite, marcasite, natroalunite, natrojarosite, pyrite, pyrophyllite, smectite, and native sulfur; in some places, the volcanic rocks have been entirely replaced by alteration products.

[40] Fish and mussels have been observed on Monowai Seamount cone as well[41] and rhizocephalan parasitic barnacles have been found at certain unspecified vents.

[40] Additionally, phytoplankton has been observed to grow after eruptions when the fallout from Monowai Seamount fertilises the waters.

[1] The chronology of volcanic activity at Monowai Seamount is largely unknown given the absence of available dating; it is not known, for example, whether the two nested calderas formed during the same eruption.

[46] Monowai Seamount is a fast-growing edifice,[47] with growth rates ranging between 0.004–0.02 cubic kilometres per year (0.00096–0.00480 cu mi/a).

[48] Monowai Seamount's magma output rate reaches 0.63 cubic kilometres per year (0.15 cu mi/a) during some periods and exceeds that of many oceanic volcanoes such as Hawaii;[47] this fast growth is accompanied by cyclical landslides and sector collapses that redistribute material down its slopes.