The lava lake within Halemaʻumaʻu at the summit of Kīlauea illuminated the vent walls on the evening of February 13, 2017. Circulation within the lava lake causes upwelling and down-welling on opposite sides of the lake. This often results in spattering on the lake surface (right), which creates bright spots on the dark, semi-solid lake crust. Circulation can also pull sections of the crust apart, exposing the molten lava beneath and creating incandescent lines on the lake surface. USGS photo, M. Patrick