'Aik kalaq' which means 'hot water' emerged in some locations around the crater of Segara Anak both nearby or far away from it. This explains the presence of geothermal resources in around the locations. It's surface appearance through weak zones as hot springs leads to the formation of stream or pond. Beside hot spring there is also waterfall in the area.
With the lake temperature of 5-7° C above ambient temperature, this lake is probably the widest warm water volcanic lake in the world. Water in the lake has Neutral ph (7-8) and water chemistry is dominated by sulfide and chloride with Total Dissolved Solids value reaching 2640 mg/litre showing the flow of hydrothermal fluid to the lake (A. Solikhin, 2010) mixed with rainwater that pour to the caldera.
