 Next to a heavily hydrothermally altered lava dome in the centre of the caldera lies the Laguna Corona del Inca . This 350 metres ( 1 @,@ 150 ft ) deep and 5 @,@ 300 metres ( 17 @,@ 400 ft ) high lake measures 2 by 1 kilometre ( 1 @.@ 24 mi × 0 @.@ 62 mi ) . The lake has probably generated the evaporite and lacustrine deposits that lie on the caldera floor . Water temperatures of 13 ° C ( 55 ° F ) obtained by satellite measurements suggest that some hydrothermal activity persists . The lake is fed by meltwater . 
