There appear to have been Rotoiti eruptive vents at the eastern end of the lake and although these are part of the Ōkataina Volcanic Centre they are now believed to be in an area of collapse subsidence outside the north western margins of the Ōkataina Caldera.
The presence of Rotoiti eruptive vents is noted at the eastern end of the lake. However, these are currently believed to be situated in an area of subsidence collapse beyond the northwest boundary of the Ōkataina Caldera.