A recent cruise of the Indonesian Research Vessel Baruna Jaya III provides news seismic data and dredged samples from the Western part of the Sinta ridge. Seismic data shows a thin and uniform Plio-Quaternary cover overlying both the Late Miocene oceanic crust of the North Banda basin and the Banda ridges (Tukang Basi and Sinta ridges). Dredged samples from the Western part of the Sinta ridge (now rising at about 3000m deep) confirm the existence of a Triassic carbonate platform and thus the continental origin of these Banda ridges. Correlations between the "on land "tectonic events and the seismostratigraphic data, pointed out the opening of the North Banda basin during the Late Miocene and then the local deformation of the Lower Pliocene sediments unconformably covered by upper Pliocene to Pleistocene sedimentary deposits. It is suggested that the Sinta ridge went down, from the surface to its present depth, during the Late Miocene time, when the North Banda oceanic crust was created.