Submersible observations, carried out in the Society and Austral hot spot regions (South Pacific) during the Teahitia II cruise (1988--1989), enable us to propose a model relating the style of volcanism to the depth of eruption on large intraplate seamounts. (1) The bases of volcanic edifices are characterized by broad flat flows formed during a high rate of discharge of a very fluid magma on the sea floor. (2) The edifices' flanks deeper than 500 m are mainly made up of bulbous, tubular pillows and large drained lava tunnels occurring on slopes steeper than 60¿--70¿. These lava flows occur on lateral volcanic vents, about 200--300 m high, along linear rift zones which are formed on the flank of the major edifices. (3) Volcanic ejecta due to hydromagnetic eruptions occur at shallow depths (500 m in height) are individual conical features built at a high rate of volcanic discharge localized along radial linear eruptive fissures called rift zones. The slopes located between the rift zones are covered by talus material are limited, and unimportant mass-wasting (sector collapse) features were observed on the edifices. The conical-shape features are the primary morphology of the intraplate volcanoes formed during edifice growth which is closely linked to the hydrostatic pressure of the magmatic column. The mean values of the slopes (11¿--17¿) of intraplate seamounts are the same as those of subaerial intraplate shield volcanoes, when the seawater hydrostatic pressure is taken into account. ¿ American Geophysical Union 1992